October 2017 - last edited October 2017
October 2017
You need to do this steps:
Clear Origin cache https://help.ea.com/en-us/help/origin/origin/origin-my-games-list-is-blank/
Restart your machine .
Run the setup file Origin with Admin rights http://help.ea.com/en/article/how-do-i-run-a-program-or-a-game-as-an-administrator/#2
How to enable Offline Mode in Origin.
-you must log in once while online. This caches your account on your machine so you can log in while offline. If you acquire a new game, you'll want to log in once online to ensure your offline cache is up to date.
-you must launch any game you want to play once while online. This ensures the game is properly set up on that machine so it can thereafter be played in offline mode.
-now you should be able to log in while offline and play your games in offline mode.
NOTE your Origin client will stay in Offline Mode until you turn it back online from the same Origin menu. In addition to this, even if you had to close your client for any reason whatsoever and required entering your Username and Password again, you will not require a connection to the internet.
More details here http://answers.ea.com/t5/The-Sims-4/Offline-Play-without-logging-into-origin-everytime/td-p/3436087
My Opinion is no more important or right than yours.I'm a gamer like you, trying to help you (i'm not an EA employee).
If you want to know us or/and come up with ideas to improve the Origin platform or/and talk about anything and many more besides,you could also visit the NEW section Origin General Discussion http://answers.ea.com/t5/General-Discussion/bd-p/origin-general-discussion-en
November 2017
Unfortunately, i've tried all of this...it still doesnt work when not connected to internet...