For a start try to run a repair of the disk with Windows Tools. Right click on the drive and select properties, choose 'tools' tab. Click on the Check Now at Error checking part. If that won't work, you can try Easeus recovery tools.. I've done a review for them sometime ago and their apps are very good. Also, try to use Get Data Back for FAT or NTFS, depends on what you need. Drive Rescue is another free app which should help.