HI.This will occur when the optical assembly becomes unstable. this ((Whole One Piece)), assembly incorporates the spin/load motor, optics housing /arm, tracking device and tracking rail. This is connected to the loading dock assembly. This 'NO Disc' or CD NOT PLAYABLE, code is the result of a failed or burned out lens. It is possible that you have a dirty lens cap. you can try using a cleaning disk in this case to confirm actual lens failure. if the cleaning doesn't restore normal reading capabilities, this will confirm my diagnosis.

You will need to have the optical assembly replaced in this case. once replaced, your unit will be able to read and track once more.