Look in Disk Mamagement does it show the disk as Raw there? It sounds like some type of corruption. Download and burn a Linux Live CD and boot from that and see if you can access you data. You can try this EaseUS Data Recovery Wizzard http://www.easeus.com/resource/repair-raw-disk.htm . It will recover 1 gig free if it works you can buy it. TestDisk Is free and a lot of people have good luck using it to fix a damaged partition http://forums.techarena.in/tips-tweaks/1352757.htm
Joe
