The sims 3 installation code lost?

Okay so I had to set my computer back to when I first got it, I know the term but it's not coming to me sorry. Any way I had had the game installed and normally I keep all the booklets and disks because I have bad luck with my computer and the sims games, but the only one I can't find is of course the only one I actually need the plain old sims 3. I had the disk but I can't find the packet. I had the game registered on the sims3.com site since I had to put the code in to register it is there a way to retrieve it? Besides buying a new game is there something I can do?