Is your cd player a Clarion ? ( usually are in older Peugeots ). If it is then remove the player from the dash then remove the top cover, you will then be able to remove the cd that is stuck in there. Then remove the cd drive on the back of the drive you will see some plastic cogs with a clear cover on top of the cogs with a screw holding it down you will probably find that the cover has broken / cracked around where the screw is and so it's not holding the cogs in properly. Just put some super glue on the cracks and let it dry then put it back together again and your cd eject button should work again.