Splinter Cell Double Agent disk is unreadable?

I play it for a while but then after a few days it says disk is unreadable. I lost all my data ( not the problem i dun think ) But i press single player, new game and when it is loading the iceland mission it makes a whirring sound, then it says, " This disk is unreadable." It has a few scratches but then i went to a store and repaired it. It still says that. Please HELP!!!!!!!!!!