Track This Thread Repair A Corrupted Flash Drive/USB

1. open cmd
2. type diskpart
3. type list disk
4. select your disk e.g. disk 1
5. type clean
6. type create partition primary
7. type active
8. type select partition 1
9. type format fs=fat32 (depending on your drive, fat,fat32,ntfs..)
10. type exit

done.