If nothing listed above works dont waste your money on a cleaning disc. Take the cover off, Locate the laser lens, get a cotton swab and dip it in rubbing alcohol. clean the laser with it and let it dry. see if it works. If not then observe whats going on when you put a disc in when the cover is off. Does it spin up? etc. See if you can see the laser light up. Dont look directly in it but you can see it from the side too, that wont hurt your eyes.
Unless, you dont think your handy enough to tacke the above, then get a cleaning disc. Also make sure the unit is unplugged while your working in there. You can get shocked if you touch the wrong stuff
