I recently found what seems to be two useful bits of software.

Test Disk, Data Recovery

and

Photo Rec

These ignore screwed up disk partitions and go directly after the data that was lost on a hard disk or memory card. Photo Rec can recover lost video as well as photos and Test Disk can go after data and make non-bootable disks bootable again.

Versions are available for DOS and DOS based Windows versions, NT based Windows versions, MAC, and Linux.

Haven't had to use it yet fortunately.

John