Try to format it again to fat16 or fat32. I would suggest fat16 it is less detrimental to the flash, so the manufacturers say.
You want to try reading this post on
recovering broken USB flash drives.
Good Luck,
Nick
P.S. all those cheaper 8gb drives from best buy use really bad components so if you decide to get a new drive get a san disk or some similar in quality (Kingston is generic flash also).