transferring sims3 from windows pc to mac?

it says  i need a code that i don't have.

Yeah I've done that but all the content is gone and none of my expansions or stuff packs are on there. I have the MacBook Air. I don't have any of the old cases from the packs so how do I get my stuff back!! ugh this is ridiculous. origin should have al my content synced to the application once I put it on the game

@rachel92698  After you install the base game, you need to click on the tab that says "Expansion Packs" and download those as well, one by one.  If you originally registered your packs, that's where they will be listed in your Origin library.  And please remember that Origin didn't exist when TS3 was released, so there's no way it would know what you've bought unless you specifically input that information.  It does share account details with the store, though, so if your packs are listed there, they should also be in Origin.

As fare as the contents of your game folder go, you can transfer most of the files from one computer to another.  I used iCloud, which has a Windows-friendly app as well as the one that's built into mac OS.  Your saves, saved sims and households, lots, and patterns can all be placed in your new game folder without issue.  You do need to redownload all of your store content, but you don't have to pay for it again.  The items will be in your account's purchase history.

I know that this isn't what you're asking, but you might want to be careful trying to run TS3 on a macbook air.  Airs are not gaming computers—they have integrated graphics and lack the cooling strength necessary to protect themselves from overheating.  Depending on your model, you might be able to run only the base game, or perhaps several of the less demanding packs.  Pets and Seasons would likely place too much strain on your mac.  And even if you got the game up and running, you'd still be much more limited than in Windows due to the way TS3 was ported into mac OS.  But if you want a slightly more specific estimate of how your hardware might hold up, you can post your specs here.  This is the relevant information:

https://answers.ea.com/t5/The-Sims-Mac/READ-FIRST-Sims-3-Mac-Help-Guides-and-Troubleshooting/m-p/4756624#M4

I payed for all the expansions I had years ago and they were installed on my Dell, when I go to expansions, it just shows me the ones I can buy. None of my expansions are there that I paid for and I’m really mad. 

@rachel92698  If the game is still installed on your old computer, you can find the product codes in your registry and then redeem them in Origin or at the Sims 3 store.  Here's how to do so:

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

If you get a message saying the codes have already been used, then perhaps you already registered them to another account.  In that case, you'd need to contact EA customer support to get things sorted out, perhaps by merging your accounts.

https://help.ea.com/en/contact-us/

Well I don't have the computer anymore but I have the hard drive.  How do I go to the registry? what do you mean

@rachel92698  You'll need to plug the hard drive into a system that can display its information.  If this is something you don't know how to do, it's probably best to take it to a store or a specialist to be read.  As for where to find the product keys, I already linked you the instructions.  Crinrict's blog post has all of the information you need to navigate to the registry and find the keys.

If the hard drive has been wiped, then there's nothing you can do at this point to recover the keys.  So unless you can convince some EA customer support rep to issue you new codes, then you're unfortunately out of luck.

@rachel92698  I'm not sure that would work.  Files are formatted differently in macs, and mac OS doesn't have a registry in the same sense that Windows does.  You might end up reformatting (wiping) your hard drive, in which case you'd have lost any chance at accessing the registry keys.

If you mean that you want to transfer TS3's installation files from your PC onto your mac, that won't work at all.  Program files must be installed directly onto a computer; you couldn't even transfer them from one hard drive to another within the same PC.