* First go to comman prompt .Start–>Run.
* There will be a dialogbox, Type command prompt in the dialog box
* Then C:/documents and settings prompt will appear.
* Then type format x (x is the driver letter) and press ENTER
* After that you have to enter the volume lable of the pen drive correctly and press ENTER.
* Then a prompt will appear.Select Y (yes) command.
* Format will start.