If your CD player repeatedly skips regardless of what CD is placed in it, or displays a constant message that it cannot locate the CD, you most likely need to realign the laser inside of the device. This process will vary slightly depending on which CD player model you have, and the most time consuming aspect of the realignment process will be the trial and error procedure of making slight adjustments to the read head and checking to see if it will now properly read the CD. CD players can also be taken to an electronics store for repair.
Open up the case of the CD player carefully and methodically. This step will vary in difficulty depending on the model of the CD player you have. Some CD players have an easily accessible case. Others will need to be opened by carefully taking out screws and clips. Be sure not to lose the screws, and to line them up in the order you removed them.
Locate the small circuit board inside the CD player. The circuit board will have a small, square shaped part with a plastic disk on top of it. This disk should have a slot meant for a screwdriver. This is the alignment mechanism, referred to as a potentiometer.
Mark a line next to the current position and direction the potentiometer is pointing in the event it needs to be returned to its original position. Insert the screwdriver and rotate the potentiometer in intervals of 30 degrees, then put in a CD and see if it will play without skipping.
Re-attach the case once you have properly adjusted the potentiometer and the CD is playing correctly. Be sure to put all screws back in their original places.