How to Repair Bad Sectors in a USBby Mickey Walburg
External USB powered hard drives are convenient ways to store data that don't require you to add on additional internal hard drives to your computer. If you use a USB drive frequently, it can develop "bad sectors," or portions of data that the computer is unable to read, and which can corrupt data on the drive. If these bad sectors are present, repair them with the computer's disk error checking and repair program.
Close any open programs and windows.
Click the "Start" button, open "All Programs," then click "Accessories," then "Command Prompt."
Type "chkdsk usb_drive: /r" ("usb_drive" being the drive letter of your USB hard drive).
Press "Enter" and wait for the automatic scan and repair process to finish scanning and fixing your USB drive.