The sims 4 - play button greyed out

Try these:

The Play button in Origin is gray

Make sure your game is updated to the newest version (see above). If that is the case and the play button is still gray, try the following things (or any combination of it)

• Restart Origin
• Manually uninstall Origin, run ccleaner, then reinstall
• Right click on the Game in Origin and hit Repair Game
• Log out and back in
• Delete Origin cache files

Source: http://answers.ea.com/t5/The-Sims-4/FAQ-Installation-Updating-and-Startup-Issues/td-p/4276949

Hi,

I was having the same trouble and looked everywhere for what to do. The game wasn't working for me for the past 5 days or so. Today, I had some time to search the internet for a solution. 

Nothing was working, so I tried a couple of different things. I hope this is what finally worked, and I'm not leading you down the wrong path.

I reinstalled origin (this step is probably pointless, but I did it anyway)

I deleted the Cache Files.

(I use a mac) Go to:

-documents

-Electronic Arts

-The Sims 4

In The Sims 4 folder, delete these cache files

After I did this, I went back into origin, right clicke'd on the game and clicked "repair game", quit Origin and it finally worked.

hope it helps. sorry if it doesn't.