Re: How do i register my sims 3 Expansions on the sims comunity without the serial code

from the FAQ

Finding your Registration / Serial Code

If you still have the game on your computer you can follow these steps to find your serial code from your registry (PC only). Credits of to Carl's Sims 3 Guide
You need to be signed in as an Administrator first.  Windows may require your permission to open the Registry Editor and if so, just click on yes.

1. Press the Windows key on your keyboard and type regedit in the search bar and press Enter. 
2. Click on 'File' at the top left of the window that opens then click on Export.
3. Choose a location and name for the file as this will be your backup registry file.
4. Click Save.
5. This backup is created just as a precaution.

Now to find your serial codes for each specific EP or SP installed on your computer:

1. Expand the HKEY_LOCAL_MACHINE folder.
2. Expand the SOFTWARE folder (Wow6432Node for 64 bit systems)
3. Expand the Electronic Arts folder.
4. Expand the Sims folder
5. Expand the EP or SP you need the code for
6. Click on ergc and in the box to the right under 'Data' you will see the code
7. Write it down somewhere save
8. Repeat above steps for each EP

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Instructions for Macs can be found here: Finding your serial key using Terminal

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No access to the serial code

If you lost your serial code and don't have the game installed on an old computer, you need to contact Customer Support.
They can be found here: https://help.ea.com/contact-us
You have the option to contact them by mail, phone or Live Chat. Make sure you have a game, a category and a platform selected for the options to become available.
For Live Chat, make sure to choose US as your country.

If you registered your game to your account, it should be easy to get the code. If not, they'll give you a new code if you can proof that you own the game. See this: Obtaining a Replacement Registration Code

other than that you will need to contact the CS reps to assist with this   as it may involve access to your account and personal  information

edit typo