I agree with mailpup.
If the DVD device is physically there Windows will detect it and the device will appear in somewhere in device manager
> If you're not seeing it in device manager and
> There are no "Unknown" or "Other" devices or devices with a yellow icon, then it's not in device manager
Only things left:
> Reseat the DVD. Make sure it's making good contact
> Check the cable connections are tight
> Check BIOS. make sure it's not somehow been disabled in BIOS
Otherwise, it's kaput :dead: