Why won't my computer read the optical disc?

There can be lot of things that can go wqrong with the disk making it unusable..
For last option try software like ISOBUSTER to save whatever that could be extracted from the drive

Was the disk burned in that same drive? If its a multisession disk and was never closed, it could be an issue. When ever I have optical drive problems the first thing I try is to clean it with the tray open but the PC off, I spray with canned air into one side so the dust goes out the other. Then I have a cleaning disk I can use that you can get at the store some are not expensive at all. It causes a brush to pass over the laser lens without touching it and removes any remaining dust (of course the PC is back on now). After that I would try uninstalling the drive from Device Manager and reboot so MS can reload the generic drivers. If it still won't read the disk then its time to take the disk to a friends house and try it there. Report back what you find. Not many people come back after given advice (to say what happened).

The Drive is not the problem ..The disk is

What codec or software was it burned in?

Another thing that comes to mind happened to me. I used to use Nero InCD to create RW disks I could erase. After having many troubles with InCD I decided not to use it anymore and treat the disks as one complete erase instead of individual erases like a floppy. The problem was I could not read many of the older disks I had made with InCD. There was a little program you can use to access those disks, or you can do what I did, install InCD just to copy and re burn your data in the more conventional way and then uninstall InCD (actually I set a restore point so I could get rid of it completely when I was done cause even after uninstall it left issues behind).