Optic discs, such as CDs and DVDs, are widely used nowadays. They are cheap, they are thin and light, and most importantly, they serve a versatile range of utility and can permanently store a large amount of contents.
However, most if not all users have more or less experienced disc reading problems that had jammed their DVD players or hung their computers once in a while. The root cause behind all these frustrations is that optic discs are optical devices. They store data by modifying the optical characteristics of the thin layer of storage material on them. Be it the original aluminum-based optic discs or the more-modern organic chemicals, it is a thin layer read by sensitive laser lights from the bottom side of the disc, which is covered by a thin layer of protective plastic. It is not hard to imagine, the entire disc is completely exposed to the environment and has the lack of protection against scratches, dusts, dirt, moisture, and other types of wear and tear. The optical chemicals are generally volatile and sensitive to the operating temperature and wears out with time. Further exacerbating the situation is that because the optic disc profit margin is so low that most if not all manufacturers have lowered their standards to cut cost. If you happen to have saved your favorite photos on a writeable CD or DVD, better check it once in a while to make sure it still works and make duplicates if possible. Chances are they do not last for decades and can wear with each use.
When a disc read error occurs, the first thing to do is to look for a way to let the disc stop spinning. Sure, if it just stops and ejects itself your disc is probably fine, but in many cases, especially when it is being read by the optical drive of a computer, chances are read errors can result in a system hang and the disc spinning at high speed in the drive. In such a situation, the last thing to do is to force open the disc tray, because the disc is likely still in its raised position and the upper part of the disc tray can scratch the upper surface of the disc, permanently damaging the storage materials of the disc. Most operating system drivers prevent this type of situation by disallowing a disc eject when the drive hangs, but if the disc never stops spinning, it can overheat and burn the optical drive out and potentially the entire system as well if you are using a laptop computer. When a spinning disc situation occurs, try to close any application programs that can potentially access the disc. Click on “End Now” if the system says the program is not responding. You are more likely to lose data and burn the drive out if the disc just keeps spinning. If that still does not stop the disc, try to log off or even shut down the system. Powering off the system would guarantee to stop the disc from spinning, and you can always eject it by pressing the eject button on the disc drive when you first power the system back on. Apparently, some systems would attempt to first boot from CD/DVD drive, in which situation a boot error is likely to halt the boot sequence and stop the disc. Or if you would prefer doing it the mechanical way, just eject the disc by inserting a pin into the tiny Emergency Disc Eject hole on the disc drive when the system has been powered off, although this is not recommended because it can potentially scratch your disc. The emergency disc eject method shall be applied only when your disc is really stuck in the drive and the drive tray cannot open up.
The next thing down the road is to diagnostic the disc to find out what happened. Handle the disc with care. Grab it only by its edges and avoid contact with its either surface. Carefully inspect to find out if there is any scratch or dirt on it. If the disc looks dirty but completely intact then you are lucky because chances are everything in it is still there. To fix the read error on an unscratched disc, find a soft, dry cloth and gently wipe off the dusts, dirt, moisture, and other types of build-ups that could affect the disc surfaces. Avoid wiping it with any type of chemical cleansers, and wait until the disc cools down before wiping it if it is hot, because the disc surfaces are made of cheap plastic that is generally sensitive to chemicals and temperature, wiping it when it is hot or with chemicals is likely to create distortion in the surface and damage the disc. In the extreme situation where only water can clean the disc up, try to run it under warm water, swing to get rid of the remnant water droplets, and let it dry on its own by placing it on a dry lint-free towel, in a disc holder or suspend it in air otherwise. Avoid using non-lint-free towels or any paper product to wipe off the water droplets on it.
If you happen to find your disc scratched, immediately locate all the scratches and avoid contact with any. If the scratches are on the reading side, chances are you need a disc repairing kit to repair the reading surface, although very minor scratches are unlikely to affect reading quality. Although not very encouraged since this could further damage the disc, you may try the disc in the drive to find out whether or not it needs repairing. As a caveat, however, you would not find out whether or not the disc is damaged until it reads through the scratch. Optical drives read from center to edge. If the scratch is near the center, you are likely to discover the outcome immediately. If the scratch is near the edge, you are probably not going to find out the outcome until the end. Regardless, if you find out our disc has been damaged in the reading surface, you are likely to recover it by using a disc repair kit that you can get for $5-10 in an office supply store.
If the scratches are on the top surface, the situation gets tricky, because that is the side where the storage materials along with a thin layer of aluminum and possibly a writing surface, a printable surface, a disc label, or it could have been painted. Any damage to the thin layer of aluminum would render the disc unusable and probably irrecoverable. On the other hand, if the scratches did not go through the surface paint, disc label, or the thin layer of writing or printable surface, then the disc is still usable, although further use of it could result in further damage. Try to examine the scratch to see how deep it is. If it is deep and you can see through the disc then this is the end of it. If you can identify some silvery color or silvery cinders around it, chances are, it is already damaged. If you merely see a shallow scratch on the paint or it does not even go through the disc label, then you are probably fine, although for painted or printable discs sometimes it is hard to tell until you try because the paint or the printable material could replace the disc plastic and any damage to it could also result in damage in the aluminum layer. As a side note, disc repair kits generally do not work for a disc scratched in the top surface because that is the side where the data is stored. Once damaged the disc data is lost even if the scratch has been repaired by a disc repairing kit.
In summary, a few tips for handling disc reading errors have been provided. Optical discs are widely used and affordably priced, but the data on the discs could be invaluable contents that you would never want to lose. The best practice is to take good care of the discs, make backup copies and duplicates if possible, and examine them once in a while.