Re: "Unable to start: Cannot start because game data is missing or damaged

@baconjr66  Please use Revo Uninstaller (the free version is fine) to clear out everything related to Sims 4 and the EA App, then restart your computer.  Reinstall the EA App.  Create a new folder on the root level of the drive of your choice, for example C:\Games is fine, but not C:\Program Files\Games.  Choose that folder when installing Sims 4.  Use the EA App rather than Steam, at least for now.

Please leave your antivirus uninstalled until you've tested the game once.

If you still get this error, please run a dxdiag and attach it to a post.

https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/