Did you select "AutoPlay" from the Control Panel? In this dialog, you are given a multitude of settings to control how Windows behaves when a disc is inserted.

But from what you're describing, Windows isn't even seeing the device correctly. When it appears in Disk Management, what drive letter does it appear as? It should be the first available letter that follows the hard disk partition(s). Or is it showing up without a drive letter assignment?

There is also the possibility that the CD/DVD driver has become corrupted. If it comes up in the devices list, you should be able to perform an "update driver software". If that doesn't work, you could try uninstalling it so that when you reboot, the "new hardware" wizard is launched to set up the device from scratch.

Well that's peculiar, Robert. The good thing is that it shows up, but for Windows to not assign a drive letter... that's odd. Did you check the drive in the Device Manager list, to see if there's any flagging for a driver error?

Does the unit show a power light, or at least make a noise when your computer starts up? If you press the eject button, does the door open? And what happens if you insert a CD or DVD and close the door? Does it try to do anything with it or just sit there idle?

As a last resort, I would pull the drive out and check for the brand and model number, then seek out drivers to download from the Internet. Then install those and see if it solves the problem. You could also uninstall the existing device driver in case it doesn't work the first time, as sometimes the existing one doesn't get replaced.

Sounds like you have already done what I would recommend

press Windows key and R
Type regedit, and then click OK.
If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.
In the navigation pane, locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
In the right pane, click UpperFilters.
On the Edit menu, click Delete.
When you are prompted to confirm the deletion, click Yes.
In the right pane, click LowerFilters.
On the Edit menu, click Delete.
When you are prompted to confirm the deletion, click Yes.
Exit Registry Editor.
Restart the computer

^ Trouble with autorun is the least of his worries... there's no drive letter assignment, so he can't even access the device through Windows Explorer. Kind of unusual situation.

Try right clicking on computer, click manage,disc management. and give it a letter