i dont think it is possible, but you could try norton system works, but i dont think that will do it also, dont put anything onto your flash drive now until your sure you cant recover it go to a computer store in your area and ask them about it, it doesnt sound like something you could do by yourself, u probobly need special tools before calling the comp store, search google and see if anyone else can do it, to check if it is even possible hope this helps !
http://www.flashfixers.com/ http://www.snapfiles.com/Freeware/system/fwdatarecovery.html http://www.ontrack.com/freesoftware/