Have you first checked all the cables and their connections?
If so, try Uninstalling the optical drive in Device Manager and Rebooting.
This should let Windows Find New Hardware and Reinstall the basic CDROM drivers.
If it's not listed in Device Manager but the front indicator light is lit, disconnect one end of the data cable and Reboot.
When the system is back up and running, reconnect the cable; this should again let Windows Find New Hardware etc.