Take a soft cotton cloth and dampen it with rubbing alcohol. Clean the surface of the DVD by making straight strokes with this cloth across the read/write surface of the DVD. This will remove dirt, fingerprints and other residue that may be impairing the performance of your DVD. When finished cleaning, allow the DVD to air dry before playing it in a DVD player.
Take a soft cotton cloth and spray some furniture polish on it. Polish the scratches on the surface of the DVD with this cloth. The furniture polish will help repair the bad sectors in the DVD by polishing the scratches and allowing a DVD player to have an easier time reading the DVD.
Take a soft cotton cloth and squirt some toothpaste on it. Do not use gel, as it will not be effective. Polish the scratches on the DVD with this cloth. The gritty toothpaste will wear away the scratches on the surface of the DVD and repair the bad sectors in the DVD. When finished polishing, clean the remaining toothpaste residue off of the DVD following Step 1.