@Razviolet and make sure your internet connection is not running through a proxy.Go to Internet Options in Control Panel > check the connections tab and make sure the proxy server is not checked. Check the internet settings again .
go to: C:\Program Files (x86)\Origin Games
-rename(change) Sims 3 to Sims 3=( or whatever you want,does not matter)
-start Origin
-now the game appear in My Games ready for Download
-close Origin
-rename(change)Sims 3 =(or what name you put) back to Sims 3
-start Origin
-and now game will be playable
Go in Game Options and unchecked the "online" box. Hit apply changes. Then rechecked the box and hit apply again.