I have used scratch removers and disc cleaners from
http://www.mapleshaderecords.com on some CD's and it worked great. I have brought a couple discs back to life.
I have NOT tried it on any DVD's, Blu's, or games, but I do not see why it would not work on them. however, like previously mentioned, any discs with deep enough scratches will not get fixed by some of these products.
Good luck!