USB Flash drives are everywhere. Compact, with storage up to 256GB as of 2010, Flash drives are portable and can store massive amounts of data. On occasion, Flash drives can become unrecognized when plugged into a USB port. That is frustrating, to say the least, but the data usually is recoverable, since a Flash drive contains a memory chip rather than a movable drive disk. A real problem occurs if the drive is not seen at all by the computer. Then, the data on the drive likely will be lost without the aid of a drive recovery service.
Make a backup version of the disk contents if at all possible.
Download a free Windows app to do a low-level formatting (See Resources). Formatting will erase the contents of the drive.
Plug the flash drive into a USB port on the computer. If detected, it will appear in the "My Computer" directory/menu after a few seconds.
Right click on the USB drive icon, then click on "Properties" from the drop-down menu.
Choose the "Tools" tab in the "Properties" dialogue box. Click "Check Now" to start the error-checking tool. Select both available options and run the program. If the program fails to complete, try the process through the command prompt.
Click "Start" and select "Run." Type "cmd" in the text box to open the command prompt.
Type "C:>chkdsk E: \f \r" (do not include the quote marks). Change "E" as the drive letter, if this is different on your computer for the flash drive. Be sure the disk is locked. Click "Enter" to begin the process.
Try to open the Flash drive once the process completes. If this fails, a disk recovery service is the only hope.
Flash drives can be defragmented, but it shortens the life of the drive by making unnecessary writes of the Flash chip.