The File Allocation Table, or FAT, is perhaps the most widely used file system on personal computers, recognized by Windows, Linux distributions and Mac OS. It's most commonly used on solid state storage devices like SD cards and USB flash drives.
Attach the flash drive, memory unit, or FAT-formatted hard drive to the PC. Go to "Start," then "My Computer" to determine what drive letter the device is assigned.
Go to "Start," then "Run," then type "cmd" (without the quotes) and press "OK." The command prompt will open. Type "C:\" (without quotes), then click "Enter" to make sure you're on the drive that contains Windows.
Type "chkdsk y: /x /r" (without quotes), where "y" is the drive letter assigned to the device. The /x parameter dismounts the drive to prevent it being accessed while scanned and the /r parameter searches for and recovers damaged sectors. Press "Enter."