HDD Upgrade Help

I have a 20gb PS3 and I upgraded it to an 80gb. I used a 32gb flash drive (brand new) and used the back up utility. When I changed to the 80gb and everything came on, and after formatting the drive, I attempted to restore my back up data and it said there was no back up data. It shows that I only have 20gb of free space on the flash drive, but I can’t re-buck up my files on my 20gb hard drive, or delete them or restore them, and if I try to manually copy files, it tells me that the USB cannot be found. Please help, I don’t want this to be wasted money, I don’t want to have to re-do everything on my games.