i think uer trying to make it bootable right??
then try any bootable drive making software.
if uer just trying to format it then do this:
FORMAT X: /FS:FAT32 /Q /V
enDrive
This will reformat the Pen drive, using the FAT32 file system(if u want in ntfs type ntfs), and label the drive PenDrive. Replace X: with the actual drive letter of your Pen Drive