Restoring your USB key to it's original state using Windows:

BOOTICE Site: http://bootice.narod.ru/

1. Download, extract, and run Pauly's BOOTICE Tool
2. (1) Select your USB Flash Drive from the list, (2) Click Perform Format
3. (1) Under Disk Mode, Choose USB-FDD Mode (2) Click Next Step
4. (1) Select a File System type (2) Click Ok
5. (1) Make sure you have backed up any important info, then Click OK, (2) Verify the drive letter and Click Yes to Proceed to let BOOTICE partition and format the USB Flash Drive

Restoring your USB key to it's original state using Linux:
A. First we need to delete the old partitions that remain on the USB key.

1. Open a terminal and type sudo su
2. Type fdisk -l and note your USB drive letter.
3. Type fdisk /dev/sdx (replacing x with your drive letter)
4. Type d to proceed to delete a partition
5. Type 1 to select the 1st partition and press enter
6. Type d to proceed to delete another partition (fdisk should automatically select the second partition)

B. Next we need to create the new partition.

1. Type n to make a new partition
2. Type p to make this partition primary and press enter
3. Type 1 to make this the first partition and then press enter
   
4. Press enter to accept the default first cylinder
5. Press enter again to accept the default last cylinder
6. Type w to write the new partition information to the USB key
7. Type umount /dev/sdx1 (replacing x with your drive letter)

C. The last step is to create the fat filesystem.

1. Type mkfs.vfat -F 32 /dev/sdx1 (replacing x with your USB key drive letter)

That's it, you should now have a restored USB key with a single fat 32 partition that can be read from any computer.