Is the scratch or multiple scratches just surface or to the golden data layer? If it's scratched to the data layer it can't be repaired. First method is fill the scratches with a special solution that fills the scratch. Second type is resurfacing with a disk doctor device.
Use furniture polish: Pledge has always worked at filling in scratches on discs for me and they use it at my girlfriend's video store for games/dvds/blu-ray
I'd suggest using toothpaste. Here's what you do: take some white, plain toothpaste and rub it all over the disc, going from the inside (where the hole is) outward. After about 15-30 seconds, wash the disc with warm water and allow to dry completely.