I am trying to install a laptop but my computer says I have no Drive D: I HAVE had one! Any suggestions?

We got a laptop and the installation CD will not play in my Drive D because my computer keeps saying "No Drive D" when I try to Run it. Any clue how to get back a drive I KNOW that I had. When I play CDs on Windows Media Player, this is the drive I put it in. Can we maybe copy it to Drive A and use that or something? I'm rather computer illiterate, but I do know that we were able to use drive D in the past.