If you did indeed format your flash device then there will be no data on it.
plug your device into your pc
then right click on my computer.
select manage
select disk management

you should be able to see you flash device here, if not it might be that you have formatted it as an ext3 which windows cannot see or if you have more that one hdd check that none of them are f drive as when you plug such a device thats the next letter windows gives your new device, if that is the case then change the drive letter for the f drive, then when you are able to see the flash drive give it another letter other than c d of f. then change your old f drive back to f drive. you might need to restart the pc a couple of time during these steps, let me know if this works. there are other things that you can try but this is the first thing you should do.

One more thing. to change drive letters just right click on the drive and select change drive letters and paths...