nicolesher0210 Do you have some sort of Steam family sharing enabled? If so, please disable it for now; these services aren't compatible with EA games.
Please also repair the game in Steam: Sims 4 > Properties > Installed Files > Verify integrity of the game files.
Other than that, please create a new admin Windows account and try playing there. Make it local, as in, don't link it to your Microsoft account or any email address. You'll be able to (try to) launch Sims 4 without reinstalling anything, but your saves and other user data won't be available.