Reflective side
If the scratch is on the reflective side of the disc, you may be in luck. Unless the scratch is a deep gauge or hole, it's likely the data stored on it isn't damaged. That's because CDs and DVDs are made with a thin layer of aluminum sandwiched between several thicker layers of plastic. The data is stored in tiny divots in the plastic that are deep down, never in the top layer. To get your disc to play, try buffing out the scratch with water and a little bit of baking soda or toothpaste. If the scratch is too big for this to work, fill in the gap in the plastic with an oily substance so the CD or DVD player's laser can scan the disc properly. Try "polishing" it with peanut butter, petroleum jelly or even the inside of a banana peel.
Label side
If the scratch is in the label side of the disc, you might think it would be less severe. However, you would be completely wrong. The problem with the label side is that it's much closer to the all-important layer of aluminum. The player shines a laser through the divots in the plastic, but that is only half of its job. The aluminum must reflect the light back to lens so the machine can convert it to audio or video data. If there's no data sent to the lens, there's no music or movie, and this isn't something a banana peel can fix. If you absolutely have to retrieve your data from the disc, it's time to call in an expert, but even then there are no guarantees.
Stop the scratches
A few minutes of prevention can save you a lot of hassle. Put your discs back in their cases when you're not using them and take time to wipe off any dust, water or soil with a lint-free cloth. .
Tags: banana peel, data stored, divots plastic, divots plastic that, layer aluminum