Maybe a room mate swapped games? Sounds fishy if it worked fine then now it doesnt work.

doesnt water damage disc?idk, never tried it

Do you have the game installed onto your hard drive?

When I used to play Cod4, I installed it onto my hard drive. However, a few days later, my disc was unreadable for some maps. I cleaned the disc, I wiped the disc, still unreadable. So I installed it and it worked.

If you don't, try installing the game onto your hard drive and see if the game works?
Try deleting it off your hard drive and then see if it works that way.

Hope this helps :/

Maybe your laser is broken. Or maybe it is scratched.

i tried to install it to my hd but about halfway through, it said that the disk is unreadable and you need to clean it or something like that, tried it a few thing and the same result. Gonna go to Game and try to exchange it, hopefully it goes my way or i have to buy a new one

Dont buy a new one thats just a fail lmfao send it back from where you baught it online or in store they have to excahnge it by law !