Very often it is because of a dirty lens or turning mirror. Maybe you could open the flap (in some types of players) and gently blow some air in there (NOT compressed air, but from a camera lens squeeze bulb or just blow in a straw) but chances are this won't work.
Best thing is have an audio shop clean the lens and mirror and see if that fixes it. You can try and sneak in there and clean the lens but it is delicate so you have to be very careful.
Cleaning disks are worthless in 99% of cases but what the hell, you can give it a shot.