Emergency (Last Ditch!) CD Repair
CDs are a lot tougher and more robust than floppy disks ever were but because the data surface is exposed on them it does make then vulnerable to damage. That said, you do need to inflict quite a bit of damage on a CD to stop it working completely. However it can and does happen, and usually with your most important CD!
A CD can have three distinct types of scratch on it:
- Scratch on the label side - This is the worse of all and destroys the data on the scratch because the reflective film stores the data. Scratches here are bad news and the disc is only good as a coffee coaster!
- Radial scratch - scratches from the middle out. Normally, unless deep, these aren't a problem because a CD has error correction and can accommodate these quite easily (because the damage is restricted to a bit or two in every byte)
- Circular scratches - These are worse than radial because they damage many bits or bytes in a track.
Repairing discs is always tricky. There are devices that will help you to fix certain types of disc scratches, however,if the scratch is on the label side, forget it, no tool short of having a backup of the disc is going to help.
The first thing to try is see if it can be read in another PC or drive. Sometimes this works and it is an especially good idea to try the disc is a CD-R or CD-RW drive as these normally have better error correction algorithms built in than normal drives do.
However, if this doesn't help, you are going to have to go to work on the disc and try to clean it and soften the scratches, hopefully allowing the laser in the drive to read the pits on the disc.
If you have a dead disc that hasn't responded to the above and you want to try to get it working again here's a little trick you can try:
First, clean the disc. Place it label side down on a clean table on kitchen roil or tissue paper (make sure there is nothing hard under the disc to damage it - grains of salt or dried cornflakes can actually damage a CD!). Now gently use either a soft cloth soaked in water or methylated spirit to clean the disc. Water works ok but I find that meths is better.
Dry the disc and check the disc at this stage ... it might work just after cleaning. If not, try phase two.
Get a tiny amount of toothpaste (less than a quarter of the size of a pea is too much - use less!), and, using a wet cloth, gently from the center outwards and clean the disc. Do it very gently and go around the disc slowly working out any scratches. This might take some time but don't rush. Do it slowly, carefully and methodically.
Once you have finished, WASH the disc in water and dry and try ... if you are lucky, it'll work. If not, you've not lost anything!
This may or may not work for you, but if the disc is unreadable in the first place it can't make things any worse, can it?
Practice if you want on a freebie disc ... add your own scratches and see if you can take them out!