Lost files and problem with floppy disc

I lost some files, have no idea why. My grandson tried the backup but something was wrong with the floppy disc. He says my computer destroys floppy discs. Then he Restored several days back but didn't retrieve my files. So used a hard disc he had backed up in June. I have the files as they were back then. Have a lot of reconstructing to do! Any ideas what happened and why my computer is ruining the floppy disc? Thanks. Also, can anyone recommend any books that can help me to understand and deal with these problems? I seem to have a lot of them!