ALright something seems odd about that.
When using your USB device, do you always use the "safely remove hardware" button on your taskbar?
What can happen sometimes is if you quickly insert / pull out the usb device when you transferred files without using the safe remove option, it can screw up your flash drive.
Do you normally write tons of info. to your USB device? That can also affect the lifespan of the device. Too many writes can cause USB keys to fail, which is a weakness in all flash memory.
It's even possible your USB device was not good to begin with, say a manufacturer's defect, or maybe even got lower quality silicon.
I would try using 1 more recovery program (a different one) just in case....and if that doesn't work, i'm sorry but you might be outta luck.