It may be your drive.
Can another computer read the disc?
If so, try this (assuming a PC with Windows):
Go to your control panel SYSTEM/Hardware/Device manager. Where is says DVD/CD highlight it and delete it.
Reboot.
Upon reboot your plug and play will see the device and re-install it. You shouldn't need the original disk as the drivers should be cached.
Once it fully boots you should be able to read the disc.
I get of-the-shelf discs every once in a while that can't be read. The above trick works. A sort of last-ditch effort which as yet to fail.
Good luck.