Use rubbing alcohol and a soft cotton cloth to remove minor smudges. Polish the disc by starting at the center and moving toward the outer edge. Use a circular motion while polishing. After the disc is clean, let it air-dry before testing.
Use furniture polish and a soft cloth to restore a CD with minor scratches. Polish as described in Step 1. The waxy residue of the furniture polish will fill in the scratches and allow a CD player to more easily read the data on the disc. Clean the disc with rubbing alcohol to remove excess residue; let it air-dry.
Use toothpaste and a soft cloth to restore a CD with more serious scratches. Be sure to use paste, not gel (the grit from the toothpaste is needed to remove the scratches). Polish as described in Step 1. The toothpaste grit will slowly wear away the top plastic layer of the CD (as well as the scratches) and allow a CD player to more easily read the data. Clean the disc with rubbing alcohol, and let it air-dry.