I thought I was going crazy today when I looked at My Computer and noticed that both my CD-RW drive and my DVD-ROM drives were missing! So I followed the usual procedures:
Restart. Nothing beats that. Check Device Manager - it was saying that both drives had an error; it was showing a small icon with a yellow arrow - when I saw this I thought I was in big trouble! Try the troubleshooter as linked in the Device Manager's properties for each item - I had already done everything it asked me to do, so it finished saying "Sorry, Troubleshooter can't help you." Fat lot of good that is. Driver updates - nope, they're all up to date, it says. Dell Diagnostics - Dell install a small partition space on the drive to hold the Diagnostics program for scanning the computer for hardware failures. Unfortuntately, it passed all the tests though. System Restore - I haven't got enough that go back far enough as I am running out of space on my computer! And finally... try contacting the OEM - so I went to the Dell Fourms for my Dell Dimension, and I found a thread that details my exact problem on this page. And when I followed the instructions about the registry, restarted and watched - it worked! Now I'm so happy because the good thing is that I solved it really quickly, and all my methodical processing, as above, got me my resolution! Anyway, thanks to the Dell Forums!