Re: Sims 3 activation code

@Katherine00511  We're talking about a disc copy of the game, right?  If you still have the product code that came with the disc—you can find it on the back of the insert inside the CD case—you can register the code now.  If the code has already been used, or you can't find it, your only option is to contact EA customer support.  If you can prove that you're the original owner of the game, you may be able to convince someone on that end to issue you a new code.  Be sure to have as much proof of purchase and ownership (photos of the disc and case, receipts, etc.) on hand as you can find.

If you bought the disc secondhand, then the original owner may have already registered the code.  In that case, you're unfortunately out of luck.  EA does not allow codes to be registered to multiple accounts or transferred from one account to another.