When I opened my desktop a couple of weeks ago and installed a 3T drive for /home, I did something wrong and the dvdrom stopped working. I had time on Sunday to tackle the problem, so I went at it.
I checked my manual for the computer and motherboard (yes, I have the manuals, and occasionally I refer to them - a miracle), and the dvdrom has to be connected to the next highest SATA port. It used to be on SATA1 but the two hard drives have SATA0 and SATA1 now. I had to get a magnifying glass and a strong light, but soon determined that I had it plugged into SATA3, as 2 and 3 were side by side. I switched the cable.
I turned the desktop on, booted it up - but no dvdrom drive. It's been years since I fiddled with this stuff, so I had to stop and think. What could it be? BIOS? I haven't looked at the BIOS in this desktop for 5 years. Got into BIOS, checked the drive settings and SATA2 was turned off. I turned it on, rebooted and Linux saw the dvdrom.
My desktop is back in action again fully.
I am relieved because I had been ripping with the external enclosure and the fan in that sounds a 747 taking off.