COD4 modern warfare broken disc

[ACHELOUS]

Hi, this is in the wrong place im sure but im having problems with installing Call Of Duty 4 modern warfare, the disc i got had seemingly attached itself to the paper sleeve it was protected by,in turn this has scored the disc with glue residue and paper, the disc wont actually read in the drive and im scared to put it in again cause it makes a terrible noise. I would have taken game back but it was an additional software that came with my mouse, which i got sent from interstate. Hoping just to be pointed at a download place for the game i have full cd key.