My USB doesnt work on any computer!

It was still working yesterday when i was working on my project but when I plugged it in my computer this morning (and even now), it display as "removable storage" and it asks if I want to format the drive or not. When I plug it into a mac, it says "The disk you inserted was not readable by this computer".

What should I do? >.< There's a 50 hours project in it and I need it!

It doesnt matter if I have to throw the USB away as long as I can retrive all the file >.<

Help please!