When i try to load a disc in my laptop it wont work please help?

when i put a disc in the CD drive it wont do anything so i go to computer and click on the CD/DVD drive and sais please insert disc into drive D: please help me out i just spent 50$ on the game the witcher 2 assasin of kings. im confused cuz the other day i downloaded diablo II from the disc and all of the world of warcraft series of games. so why wont it take and movie or this other game please help.