Erm, did you check you bios to make sure it was detected?
If so, then try going to Start > Right click on My Computer > Properties > Device Manager > Right click > Scan for hardware changes.
This will tell you of any errors or hardware connected that is not responding or is not installed correctly.
Also in device manager make sure the DVD/CD-ROM Drives drop down has something in it.
If it does, then there should not be a problem. You could also right click on the drive in DVD/CD-ROM Drives and click on uninstall. Restart the computer and windows will install it again. Then if nothing, the DVD is stuffed.
And CHECK THE CONNECTIONS to your motherboard. Open the case > make the sure sata cable and power cables are securely in and in the bios make sure the DVD drive is the first boot device, then a HDD or SSD depending on what you have.
Hope this helps!