If your car CD player is not playing Cd's and is not reading disc's you insert, it is probably time to clean it's laser lens. I suggest the easiest way to clean a laser on a car CD player, is to use a cheap cleaner disc kit. A cleaner disc, is a special type of disc that is designed to clean the laser, without having to open the CD drive apart.
Instructions on how to clean your CD player, using cleaner disc:
1)The cleaning kit should include the following things: a cleaning disc and a cleaning solution, in a small rectangular bottle.
2)Pour a sensible amount of cleaning solution onto the disc's cleaning brushes.
3)Then insert the cleaning disc into your faulty car CD Player and play a music track. As the music track is playing, the disc brushes are spinning really fast and are cleaning your laser lens. Wait for 1 minute to complete the cleaning process and then eject the disc out.