Live software that recovers data when Operating System crashes?

"I have had some luck in the past using System Rescue CD - It is basically a live Linux disk with PhotoRec recovery software.

That being said, I sometimes have problems and by far, my favourite way of file recovery (if a disk is still readable) is to just get out the CD, put it in a working Windows computer and use either Recuva for the light / accidental deletion job, or R-Studio for anything half serious as I have not seen anything better."

"Depends on your OS. for windows acronis trueimage (there's no free version), macrium reflect (there's a free version) or any number of free imaging tools will work.

With linux bubackup might be worth looking at, or file level backups to tarballs"