DIY guide to recovering corrupted data from your flash drive

DIY guide to recovering corrupted data from your flash drive

USB flash drives have revolutionized the way we transfer and share information with one another. Many people use these devices to store important files, pictures, and data without saving it on a backup mass storage device. Because of this many people lose valuable virtual belongings when the USB drives become corrupted, have read errors, or become unformattable. This could be for a variety of reason, ranging from viruses to improper peripheral device software removal. Regardless, vital data is missing and it needs to be recovered one way or another.

Let me start by saying I feel your pain! I remember working a huge writing project in college computer lab. (I was on a tight budget at the time and couldn’t afford my own laptop). So naturally I was saving my progress on a USB drive (Lexar Media). When I was finished I was pretty tired and accidentally logged off before ejecting the drive. The next time when I tried to use it, it showed up as a Removable drive rather than the usual Lexar Media drive and when I tried to open it, it said the drive was not formatted. Under Properties, it stated 0 bytes free and used space and file system “RAW”. Apparently the there was a bug in the Windows OS I was running on that corrupted the flash drive when it is removed without proper eject. There are literally hundreds of similar scenarios that people have run into throughout the years. Some things work, others really, really don’t. In this article we will be covering a couple of reliable methods you can use from home without paying hundreds of dollars with a Data Recovery Firm.

Now some of the following instructions will involve sensitive lines of code that could cause serious damage to your USB as well as your computer system if executed incorrectly. The makers of this blog and its contents are not responsible for any damage caused to any computer system or Universal Serial Bus devices. Never fear though! Just take your time, read through it twice, and leave a comment if you’re not absolutely sure about something before proceeding. I will reply!

Contents

Flash Technology – What is it?

USB Generic Troubleshooting – Tips and Advice

Data Recovery – Fixes and Procedures:

Two Drives With the Same Drive Letter

Check Disk for Errors

Format a Flash Drive

Recover a SanDisk Drive

Using Data Recovery Software

GNU ddrescue on Linux

 

Flash Technology – What is it?

Flash memory is a type of electrically erasable programmable read-only memory or EEPROM. It is non-volatile memory that memorizes its value without having to induce power. Flash drives are commonly used to store files and other objects on portable devices such as mobile phones, portable music players, USB drives, digital cameras, and various others. Flash memory electrical write/read/erase behaviors are drastically different from other normal memories, such as random access memory (RAM). With flash, the memory cells can only be written to a limited number of times, typically between ten thousand and one million times; Afterwards they typically become more and more unstable as they wear out.

There are currently two types of flash memory:

NOR flash – Permits and supports a fast random access speed, but at a very high cost.

NAND flash – Carries a larger storage capacity and achieves excellent execution for large read/write operations .

Both of these flash memory types have a common characteristic: Each bit in a flash chip is appointed a logical (1) where only a write operation can change its value from a (1) to a (0). However, the only method of performing this change is to go through an erase operation. NAND flash memory chips are compartmentalized into blocks. Each block has a predetermined number of pages which are fixed and scaled down into regions for storing data. There is also a free space region which is responsible for holding the status of the data region.

Erasing leaves a memory block that is filled completely with (1)’s. In NAND flash, erase blocks are divided further into pages. A page is usually a multiple of 512 bytes in size, to emulate 512 byte sector size commonly found in file systems on magnetic media. Additionally, a page carrying a surplus of 16 bytes of “out of band” storage space which is generally used for error correction and storing meta data. Some flash disk drivers use the concept of zones5 . A zone is a group of blocks, usually 256 to 1024. Contrary to blocks and pages, a zone is just a logical concept, there is no physical representation.

A NOR flash memory device functions differently by permitting bits to be wiped out individually until every bit is cleared. In NAND flash, only a few writes cycles are written to each page before the page’s content becomes undefined and has to wait for the next erase pass by the blocks where the page is located. So each time data is changed, the new data must be written to a different and available page in a different location. The old page where the data was written originally is known as a dead page. When a period of time has gone by, the amount of dead pages accumulated is reclaimed by the system, which initializes an erase operation to make the dead pages available again.

Flash memory has gained a lot of popularity during the past decade, because of its storage capabilities which have already reached multiple gigabytes of data, its fast information access speed, its non-volatile memory makeup, portability, durability, low power usage and its relatively low market cost.

USB Generic Troubleshooting – Tips and Advice

Have you done this already? Here are some general protocols for dealing with USB technical issues. Make sure to read through before attempting our further, more intricate diagnostics.

Back Up Your Data

A USB flash drive is just like any other computer hard drive or memory storage device. After time, it could become corrupted, fail, or break. Never completely rely on your USB flash drive to hold all of your most important information. Back them up on your home or office computer and a secondary portable hard drive to make sure you’ll always have a copy of your files. There are also a number of growing online mass storage sites where you can upload your information. Since, it’s through the internet, there’s less of a chance of data corruption, but a bigger risk of breached security. Either way, make sure you have a backup plan for your most important data.

Try It On Another Computer

If you’re having trouble opening your USB drive on a computer, try it in another computer. Pretty simple huh? Many times older computer models lack the specific drivers and software to properly utilize your flash drive. Computers sometimes are dealing with their own bugs and internal software issues that could be attributed to a virus or similar malware. In either case, it could just be your computer!

Never Remove A USB Drive While Data Is Being Transferred

Under no circumstances should you remove the USB drive while data is being transferred. Go to Safely remove hardware, stop the USB drive and when it says it is safe to remove it, then remove it. Always remove the USB drive after stopping it. If for some reason your files do not work, transfer another copy of the file with a renamed version – it may work. If you delete the file and re-transfer the same file with the same name and size, it probably gets written to the same area and will not work. A different name with a different size gets written to another area and can work. It’s better to transfer two copies of your file anyway.

Scan Your USB Drive For Possible Viruses

Like your computer, viruses can corrupt files located in your USB Drive. It’s important to check them just as often as you check your computer for viruses. Use an antivirus software to periodically check your drive and remove potentially harmful malware. If you are unable to remove a virus found on your USB Drive, format the USB Drive to make sure it is clean. Any computer you plug the USB drive into may also become infected so make sure you act quickly.

Try To Open A Corrupt File In Another Program

Sometimes a file you are trying to access may be corrupted and will not open correctly. In most cases, the file is damaged and isn’t repairable but there is a trick you can try. Double-click on a file in your USB drive and when it doesn’t open correctly or you get an error message, right-click on it and select the Open With option. It will give you a list of programs or a option for you to select a program. Try to open with another program that might be able to read the file better.

Data Recovery – Fixes and Procedures

Typically there are a few causes for USB drive error/corruptions. We’ll first go through the most likely and easiest methods to analyze and repair corrupt USB flash drives work. Then we’ll take a look at some of the more complicated methods to recover lost data or files from more serious USB flash drive error issues.

Two Drives With the Same Drive Letter

A computer will assign a drive letter (E, F, G) to a flash drive when plugged it in. If one of those drive letters is already in use, a different one will get assigned. So if a backup drive set at drive letter F, then the next flash drive installed will get assigned either E or G. Sometimes however, this process does not perform correctly and can cause the USB flash drives to not work or give an error message.

  • To fix this from a Windows PC, click on the start menu, then right-click on My Computer.
  • From there, click on Manage. The Computer Management window will then pop up.
  • Click on the Disk Management option.
  • In the right-hand panel, you should see all the attached drives listed. Right-click on the drive that you want to change the drive letter on.
  • Click on Change Drive Letter and Paths.
  • Click on the change button.
  • Finally, select a new drive letter. Windows will ask you to confirm, and click yes.

Check Disk for Errors

Windows has dedicated disk error software, labeled Chkdsk, installed for fixing basic drive corruptions. Chkdsk might take a bit of time to run, depending on the number of files and folders, the size of the flash drive, and disk performance. You can run Chkdsk from from the Command Prompt, or My Computer.

Chkdsk from Command Prompt –

 

  • Click Start, and then click Run.
  • In Open, type cmd, and then press Enter. This will open the Command Prompt.
  • Type chkdsk e:/r, and then press Enter. The chkdsk command checks a disk for structure corruption. The e: tells it what drive letter to use and the /r tells it to repair the issues it finds. Make sure you type in the respective letter to the drive to wish to scan.

Chkdsk from My Computer –

  • Double-click on My Computer.
  • Right-click on the drive you want to check.
  • Click Properties, and then click Tools.
  • Under Error-checking, click Check Now. A dialog box that shows the Check disk options will then appear.
  • Select the Scan for and attempt recovery of bad sectors check box.
  • Click Start.

Chkdsk will report back what it has done. It will give an Exit code of either 0 (No errors were found), 1 Errors were found and fixed, 2 (Disk cleanup, such as garbage collection, was performed, or cleanup was not performed because /f was not specified) or a 3 (Could not check the disk, errors were not fixed because /f was not specified.

Afterwards, go to My Computer and check out your flash drive. This is the most common method to fix corrupted drives.

Format a Flash Drive

Formatting is a very reliable method to restore the file structure and functions of a USB flash drive to their original manufacturers settings. Unfortunately, formatting the USB will ERASE all the files previously saved on your disk drive. Pictures, documents, and video will be unrecoverable after this point. But If you’re looking to really just recover the drive but never really had anything important on it, this is the quickest and most efficient method of doing so.

Format a USB drive from Command Prompt –

  • Click Start, and then click Run.
  • In Open, type cmd, and then press Enter. This will open the Command Prompt.
  • Type Format/x G:. Here G: refers to your removable disk drive letter.
  • Press Enter.

Format a USB drive from My Computer –

  • Double-click on My Computer.
  • Right-click on the drive you want to check.
  • Click Format.
  • Choose what type of File system you want. If your flash drive is less than 2 GB, select FAT, if your flash drive is 2 GB or higher, select FAT32.
  • Select Quick Format.
  • Click Start.

Your USB flash drive should be cleaned up and ready to go! Remember to take a look at USB Generic Troubleshooting – Tips and Advice to read through a few basic precautions to take with your drive and prevent corruption from reoccurring.

Recover a SanDisk Drive

While we try to keep tutorials generic without ‘naming names’, one USB brand encounters so many error issues and functional break downs, we had to give it its own section. We’re talking about SanDisk. Statistically, these flash drives are the biggest headache in the portable memory storage industry. People encounter so many problems with these drives that it would seem opening the Internet browser the wrong way would corrupt them. Ok, maybe we’re exaggerating a little bit, but it’s not that far off. In this section we’ll cover a SanDisk drive that could not be recovered through Windows using Disk Check or fixed with Data recovery software. This method will not work on USB flash drives from any other brand.

Usually with a SanDisk flash drive corruption, you’ll get errors like Please insert a disk into drive F: or There is no disk in drive F, Insert a disk, and then try again when you click the drive letter in My Computer. Opening the Disk Management component of the Computer Management console shows that the drive is connected, but there is no unallocated space to partition or format. Other things about the disk look normal. It shows up in the Device Manager as working correctly, without any warnings.

Ok, let’s get to fixing!

  • You’ll first need to download the SanDisk U3 Launchpad.
  • Click Save File and save it to your desktop.
  • Double-click LPInstaller.exe
  • Click Next.
  • Select Accept and then click Next.
  • Select Yes, backup and restore all data. This will restore all your data and files after it is reformatted. Or, you can click on No, do not back up data that is currently on the drive. This will erase all data and files saved on the drive.
  • Click Next.
  • Click Next after confirmation of Installation Options. Do not unplug the USB while installing or you will permanently destroy the drive.
  • Click Finish after the Installation is completed.

 

Check your recovered SanDisk flash drive by navigating to My Computer and clicking on your Drive Letter icon.

Using Data Recovery Software

Data Recovery Software is composed of special programs dedicated to retrieving files and data from corrupted flash drives or hard disks. There are several companies that commercially distribute this type of software for pricing that vary from the low twenties to hundreds of dollars. There are also quite a few free data recovery softwares out there that perform just as well. That being said, tread carefully on which recovery software you decide to use. While there are many legitimate sites that sell this software, there are many others that are nothing but a hoax. I’d suggest staying away from buying data recovery software and focusing on free versions. On top of that I’d suggest using the other methods mentioned first since there is always a danger in downloading software from the Internet.

GNU ddrescue on Linux

If you have a host computer running Linux OS then GNU ddrescue can recover your USB data. Much like the Window’s Chkdsk, but only better, GNU ddrescue is an efficient data recovery tool with the most sophisticated block-size-changing algorithm available. It can technically be classed as a data recovery software but it runs from your Linux terminal. It copies data from one file or block device to another in a stable and safe way. GNU ddrescue does not write zeros to the output when it finds bad sectors in the input, and does not shorten the output file if not asked to. So, every time you run it on the same output file, it tries to fill in the gaps without wiping out the data already rescued.

A failing drive tends to develop more and more errors as time passes. Because of this, you should rescue the data from a drive as soon as you notice the first error. Be diligent because every time a physically damaged drive powers up and is able to output some data, it may be the very last time that it ever will.

Here we’ll be rescuing a whole USB disc using GNU ddrescue from an Ubuntu Linux terminal.

Open the Terminal.

Locate information on your current devices and partitions (USB Device name, DVD Mount, USB Mount Point, USB File System, and ISO or DVD image). To do so, run:# dmesg | less

# dmesg | egrep -i ‘cd|dvd’

# fdisk -lIn this example, we’ll be using the following device name:/dev/hdb

Run the following program: ddrescue -f -n /dev/hdb logfileddrescue -d -f -r3 /dev/hdb logfilefdisk /dev/hdbe2fsck -v -f /dev/hdb1e2fsck -v -f /dev/hdb2

 

This is a generic summary of the steps involved. Your drive may have many more components and partitions involved. In which case, your can visit GNU ddrescue to determine the various following commands.

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Vincent Clarke

Vincent Clarke is the Universal Serial Bus (USB) Guru for USBtips.com. When he's not writing tutorials and catching up on the latest USB news, Vincent is busy preparing his next blog post and answering USB questions from his readers and subscribers.

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