@CzNika Is it possible you originally registered the expansion packs on the old Sims 3 site? That site and Origin share information, so your codes would count as used even if you never used Origin at the time. In that case, you'd need to merge the old account with the codes in it into the new account that has your base game, unless of course your packs are already in your Origin library. Please check: it's not always obvious the packs are there until you try to download them.
Otherwise, you can contact EA customer support to have your accounts merged; support may also be able to help if you can't find the old account. Take a photo for each pack with the disc, its case, and the product code showing, and upload the photos when you submit the help request.
https://help.ea.com/en/contact-us/
You can set the location in the upper right corner of the browser window to U.S. or U.K. to get more contact options. Live chat should always be available other than on a holiday like today.
If you can't recover your packs and really want them back, you can purchase them from Origin. They're 50% off right now. That's not nearly as good as using your existing packs, but at least you wouldn't need to track down disc copies.
