It looks like you need to unplug it in 1-2 places and remove the drive from the chassis, then replace a belt. It may have slipped off. I had an older Pioneer single disc do that.
Are you saying the tray opens but no play, no registration or that is spins and plays but the tray won't open?
Liberty Electronics on eBay probably has your read ass'y, I see lots of them in my search email, he's promarily a read ass'y and hybrid amp pack seller.