format could possibly have had a kink (has happened to me before)
go to file manager >right click on 'This PC' >select manage >select 'Disk Management' >and check if theres an extra drive there (D drive, Edrive (whatever you had your flashdrive set to)) and see if it says 'unallocated data' or something similar.
if so, make a new volume on it by right clicking and select 'make new volume'
if it does not show up then most likely a dead drive unless someone else comes up with a solution. it would help me out a lot aswell, i have a brand new usb 3.0 64gb flashdrive laying around that does the same thing :/