Try a different CD/DVD...a data disk and or a music disk.
Does it read those ?
How old is the drive they all fail eventually.
One simple thing you can try is Control Panel/System/Hardware/Device Manager...find the drive, right clik it and select remove. You will see a warning...ignore it and re-boot
Windows will automatically re-install it.
If this doesn't work chances are it's failing. The only way to find out for sure is to swap it into a working machine.