Does the player make squealing noises or is it totally quiet? Squealing noises may indicate that the player is trying to synchronize with the disc but can't due to an obstruction on the lens or in the laser path inside the pickup or a defect in the pickup. This can also be caused by an intermittent signal problem due to a faulty ribbon cable.
Totally silent means that the photo sensor is not getting any usable input from the laser at all, meaning that the pickup is "blind" for lack of a better word.
This can be caused by an obstruction of the beam by foreign matter on the lens or inside the pickup all the way to a marginal or failed laser diode and/or photosensor array. This can also be caused by a bad ribbon cable with one or more severed traces.
You could try to clean the optics. This is the most common malfunction as far as i know in all disc players. It would involve taking the cover off and finding a way to expose the lense, and then cleaning it with a very gentle brush. some players have a cover for the lense that swings to the side during playing, this greatly reduces the chance of dust accumulating, but its still worth the try.
If you actually see dust on the lense, then its just that simple. clean, close, play.
It may also be worth your while to check on the small shafting that guides the carriage of the laser pickup. Dirt, grome, dust and solidified lubricant can cause stoppage of the carriage and the laser eye then fails to read the next track. Please refer to the image below.