You'd better recovery files, after that reformat the partiton to ntfs, then you can access the drive again.
I found a data recovery software for beta (free), which compatible with latest Windows 7, it can recover files even if you deleted the files from Recycle Bin, formatted the partition, the partition lost, partition became RAW, partition cannot be accessed, etc. I have tried it, works like a charm. It ends at Feb 2010, download it quickly from http://www.easeus-software.com/drw-beta/