To clean a dirty CD, pour a few splashes of rubbing alcohol on a soft cloth. Take the cloth and wipe from the center of the CD to the outside edge. Repeat this process until you have covered the entire surface of the CD. This should remove all dirt and other residue that is affecting the performance of the disc. If the CD is not completely clean, add more rubbing alcohol to the cloth and repeat this process. Let the disc air dry.
To polish a lightly scratched CD, spray a soft cloth with furniture polish and wipe from the center of the disc to the outside edge. Continue to do so until all of the scratches on the disc have been coated with furniture polish. Then clean the CD using rubbing alcohol as described in step 1.
To repair a moderately scratched CD, squirt some toothpaste on to a soft cloth and rub the toothpaste into the surface of the CD. Apply pressure to the cloth when rubbing, and the toothpaste will slowly smooth out the scratches on the surface of the disc. Once all of the scratches have disappeared, finish by wiping from the center of the disc to the outside edge. Then clean the CD using rubbing alcohol as described in step 1.