Repair and fix damaged CD
Compared to floppy disks, CDs are pretty tough to fix if they get damaged. On the plus side, they are unaffected by magnetic fields and the plastic coating on each side of the disk is more resistant to fingerprints, spilled soft drinks, and other contamination than the magnetic media inside a floppy disk. In addition, there's no shutter for dried soft drinks to stick closed, as there is on a 3.5-inch floppy.
However, CDs are anything but indestructible. They need to be kept clean and scratch free. While the CD format's built-in error correction will deal with minor problems, a major scratch or dirt build up requires your action to clean.
The most delicate side of a CD is the label side. Surprised? You probably thought it was the side the laser hit. However, the label side is the side closest to the shiny reflective layer that underlies the recording layer. The reflective coating is critical to the functioning of the disk and only a thin lacquer coating protects it. The read side is protected by a thicker coat of plastic that is designed to minimize the effects of scratches.
Most of the time, when a CD suddenly refuses to play, it means that dirt, fingerprints, or scratches on the CD are interfering with the drive's ability to read the disk. Wiping the read side of the disk from the center outwards with a mild soap and water solution, or a cleaning solution made for CDs, and a lint-free cloth will usually clean off dirt and fingerprints. The operative words here are "wipe", as in gently, and "from the center outwards." Don't scrub and don't work in circles; work from the center all the way out to the edge.
Don't immerse the disks in water to clean them. More importantly, don't try to clean your CDs by putting them through the dishwasher! (Don't ask me how I know that. Just don't do it, okay?)
While people have reported success with everything from toothpaste (to polish out scratches) to floor wax (to fill deep scratches) you're probably better off investing in a disk cleaning and repair kit to deal with scratches.
There are special disk cleaning kits available that will clean disks and repair some scratches, especially scratches on the read side. These cost from $10 to $30 dollars at record stores, video game stores, and computer stores. Among the brands are Game Doctor, Disk Repair Pro and Universal Game Repair Kit. These kits usually include cleaning solutions and a mild abrasive for polishing out scratches on the read side.
There are also repair services for CDs which can attempt to fix your disk for a few dollars a disk. For example, Skippydisc at www.skippydisc.com or Oh My Disc at www.ohmydisc.com. (Acronis does not recommend these vendors; we provide their names for informational purposes. Use these products at your own risk.)
Damage to the label side of a disk is much more difficult to fix and, in some cases, not even the repair services can do anything with such a disk. A cracked or broken CD is pretty much hopeless and you can damage your drive by trying to play one.
Of course, the best protection is prevention. Treat your CDs gently, handle them only by the edges and store them at room temperature in a protective case or sleeve.
If you have a damaged CD that you successfully repaired, you should copy the contents to another CD if possible. Keep the repaired disk as a backup.