Re: i have a used sims 3 game and it won't download

The base game ? 

It depends if the base game requires Origin or not. Does it say that an Internet connection and Origin are required on the box ? If so, then it's a version that can only exists on one account. The newer games are all tied to an Origin account and can only be installed/played with that account.

You have two options:

1. Ask your friend if they are willing to also give you their Origin account 
2. Try getting a replacement code from EA for $10:  https://help.ea.com/article/obtaining-a-replacement-registration-code

If you do have the old version which doesn't require Origin, you should be able to install the game but not register.