Why can't I install my Sims 2 games? Computer: Insert correct CD ROM?

I have a Windows Vista & I think it's been around for about 6 years. I tried to find a solution to my problem on the web but I haven't came across anything that suits me. I had my Sims 2 games for some years now & I have never had a problem with them before. I got them from Wal-mart so no they're not knock offs. Plus, I've uninstalled and reinstalled my games on this computer plenty of times. Could it be my drive? What can I do to fix this problem? I am desperately bored & I miss playing the Sims. Please help!