try Turtle Wax, if the scrach isn't bad enough.
Steps
1. Put a little Turtle Wax on the disc
2. rub the turtle wax, with your finger, around the bottom of the disk
3. Take tissue and make sure ALL of the turtle wax is gone, rub all around the disk,even if ther're a speck of dust, it's important becuase it might mess up ur system up.
4. try the disk out.
Thanks to my 8th Grade General Music teacher, for having a lesson on it.