Ugh! Im soo mad! Gamecube game help!?

The person that owned it before may have had it buffed. Meaning the plastic layer of the disc grinded away to help its readability. I would try taking a damp gentle cloth and stroke it. Form the inside out, i straight lines. Rotate the disc as you do this. When finished. Try it. If it does not work. Try a diffrent game in the system. If that works, you got a bad disc.