Sims 3 serial code

Hi,

I downloaded Sims 3 through Origin and my account isn't linked to The Sims 3 so the game doesn't automatically register on The Sims 3. I searched my email from Origin but it didn't come up with any serial code on the email and I cannot find the code anywhere. I found all of the other codes and got them registered on The Sims 3 (I have two accounts, one for Origin and the other for The Sims 3) but I can't find the base game one! Its really frustrating me and I really need help!

Thanks

ALSO

When I do the regedit thing it doesn't work, 'Elecrtronic Arts' doesn't show up as a folder.

When I go on Origin and go to the 'i' on Sims 3 the code doesn't show.