TS4 is not launching - Help

slavichorsegirl​  Please make sure that your EA and Steam accounts are properly linked to each other.  Try to sign into any EA site using your Steam credentials.  If you land in the correct EA account, they're linked; if anything else happens, let me know.

Please also disable any family sharing or similar you've enabled in Steam.

If that's not the issue, please open both the EA App and Steam as an admin: right-click each desktop shortcut and select "Run as administrator."  Make sure both have loaded fully before trying to launch Sims 4 through Steam.

If that doesn't help either, please repeat the above, except in a new admin Windows account.  Make it local, as in, don't link it to your Microsoft account or any email address.  You should be able to (try to) launch Sims 4 without reinstalling anything.

If you still can't play, I'd like to see that dxdiag, or rather, a new one you run after doing all of the above.