CD key Lunacy

I'm just getting back into the Sims and am loving it again, but I'd like to download the Create a World tool. But I can't because the site says I never registered my copy! I've tried to register using the CD key on the back of the manual, and I am sure it's being entered properly, but it always is invalid. My theory is that I registered the key on another EA account, as I remember registering the game on the site when I first bought it. However, I believe this account is now inaccessible because the associated Email Address was hacked. What do I do? Should I ask for a new CD key? I only own the base game, no expansions or stuff packs.