ORIGIN ISSUE? Origin says game is not its not installed

@GordonBFreeman82  Try doing a clean uninstall and reinstall of Origin:

• Quit Origin, then right-click on the Task Bar and open the Task Manager.  Scroll through looking for Origin entries.  If you find any, click on them and End Task.
• Clear Origin's cache.
• Download Revo Uninstaller (the free version is fine) from here.
• Launch Revo, select Origin from the list, and click Uninstall.
• When it finishes uninstalling, select "Moderate" under "scanning modes," and click Scan.
• If Revo finds any remaining registry entries, select all, delete, and click Next.
• Revo will display "Remaining Data and Folders."  Select all of them except for the "Origin Games" folder, if it appears.  (This is where Sims 4 and other Origin games are installed by default.)  Delete the rest.
• Close Revo, and restart your computer.

Next, download the full Origin installer and run it.  Here's the direct download link:

http://download.dm.origin.com/origin/live/OriginSetup.exe

Be sure to run both the installer and Origin itself as an admin: right-click on each and select "Run as Administrator."

If this doesn't help, please open your Origin game library, right-click on the Sims 4 icon, and take a screenshot of the options you see.  Please also let me know whether your game is from Origin or Steam.