There are two possibilities:
1: BIOS needs updating.
I highly doubt this is the issue but there is an older BIOS update for your computer listed on Dells website. I would try running their scanning software before running the BIOS update because there is some risk involved when updating a computer BIOS. The scan and updates can be found here: http://www.dell.com/support/home/us/en/19/product-support/product/inspiron-m731r/diagnose
2: ODD has gone bad.
I've rarely seen this happen in the thousands of computers I've work on but ultimately it is mechanical in nature and is well within the realm of possibility. (Could just be from a bad batch of ODD's) That being said, you can get used/new ODD's dirt cheap. Heck, I literally have dozens of these things lying around I'll give you one free if you pay shipping, I'm absolutely serious.
Anyways, often times, you can replace an ODD by unscrewing one screw on the bottom of your laptop. Usually indicated by this symbol.
(sorry for the poor quality, it's all a quick search provided.)
Then simply slide out the old one, take off the mounting bracket and put it on the new ODD. It's almost as easy as upgrading RAM.
All of this aside, what do you need the ODD for? What software? If you have access to another computer with a working disc drive, I can give you a couple workarounds for getting the software off the disc and working using a USB or Virtual CD drive.
Still under warranty? – i_am_root – 2015-06-16T00:17:04.777
I'm not sure... It may still be under the manufacturer's warranty, but it was purchased from a discount outlet which definitely doesn't cover anything past thirty days. – Reinstate Monica – 2015-06-16T00:25:40.953
What OS are you running? Win 8? UpperFilter registry trick doesn't apply to Win8, only vista (and below?) if my memory serves correctly. – BiTinerary – 2015-06-16T01:22:51.463
@BiTinerary Windows 8.1 – Reinstate Monica – 2015-06-16T01:24:05.580
@BiTinerary The LowerFilters Registry did not appear, else I would have removed that too. The device does not show in Device Manager. This does appear to be a problem at the BIOS level, so I'm not sure this has much to do with the OS. – Reinstate Monica – 2015-06-16T01:34:19.433
I've only ever seen this issue crop up in Vista but regardless, Have you done anything with the LowerFilter? See here: http://tinyurl.com/28ohgnu This is caused by the registry keys tied to drivers so the issue could potentially be solved if you install recent updates for Win 8 (sometimes updates drivers). Has the drive ever worked? Does the drive show up in Device Manager? If so, you could try deleting it, rebooting and it should reinstall itself. However, none of these solutions explain why it's not available in the BIOS. Which may indicate a bad ODD, this is extremely rare however.
– BiTinerary – 2015-06-16T01:35:05.570@BiTinerary The ODD has worked before. I'm not sure how long this has been; it's just that now that really need that Optical Drive to work. I had the same problem installing another program from a CD, however I managed to get that one installed a few days later when I noticed that the drive was being detected all of a sudden. That went away, however, and now I'm at the same problem. – Reinstate Monica – 2015-06-16T01:41:30.793