It would indeed help if you’d explain exactly the damage done! I can only imagine it as acetone melts plastics, but the actual severity is impossible to guess!
If it’s only a surface damage, and if toothpaste surfacing fails, try a professional re-surfacing service. In some areas you can even buy a CD/DVD re-surfacing hand tool, they don’t come very cheap but for your thesis I guess you’re kinda motivated.
Just a hint for next time: NEVER leave important data on a single medium only, ALWAYS use [I]at least[/I] TWO media (HD + DVD, CD + DVD, HD + USBpen, etc…) - and when archiving, always make at least TWO copies on different media makes.