Re: how to recover previously

@SAVAN2015  If the packs are registered to your Origin account, you can download them onto your new computer.  Just sign in, download and install the base game, then click on it in your Origin library.  You'll see a tab at the bottom of the screen labeled "More"; click on it, select Expansion Packs (or Stuff Packs), and press the download button for each pack you own.

If you own disc copies of TS3 and never registered your packs, you can still do so now.  There are codes printed on the backs of the inserts inside your CD cases—add these to your Origin or Sims 3 store account, and they'll be available for download from your Origin library.  If you've lost those inserts, you can still find the codes in your old computer's registry (Windows) or via Terminal command (mac OS).

https://sims3.crinrict.com/en/2013/09/how-to-find-your-serial-number.html

https://bluebellflora.com/finding-your-serial-key-using-terminal/