Help with DVD problem, please.

I got a DVD, never used with cellophane intact, produced in 1993 on ebay. I thought maybe, since I didn't get a DRM warning, it predated DRM, and I could just copy it to my hard drive, so I did. Both the copy and the DVD are now corrupted and unplayable. I want to fix the DVD then rip it to my hard drive. Googling gives plenty of suggestions for ripping but none for fixing. Please help if you can. Thanks.