Please Help

I have a Sandisk 8 GB Titanium Cruzer. Suddenly when i insert it in to the USB i get the message, you need to format before using, do you want to format now?

I am running Vista. When i look at properties it shows the driive is completely full. It also shows that I have 0 used bytes, and 0 free space.  I have about 2 GB of data I would like to recover. How do I do this?