Place a couple of paper towels on a desk or table. Lay the CD on the paper towels with its label facing down.
Place a small dab of toothpaste that contains baking soda on a clean, dry, lint-free cloth.
Rub the CD's scratch gently with the cloth. Rub along the scratch slowly, starting at the center of the CD and moving outward towards the edge.
Rub the scratch several times. If you discover that the cloth does not have enough toothpaste, apply more toothpaste to the cloth.
Take the CD to the kitchen or bathroom. Turn on the faucet and let the warm water begin to flow.
Hold the CD under the flowing water and wipe it clean using another clean, lint-free cloth.
Remove the CD from the water and allow it to dry. When it dries, gently wipe it a final time with another clean, dry, lint-free cloth.
Place the CD into the computer or CD player and see if it plays. If it does not, the scratch may be too deep to repair using this method.