LiaKnow 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 can keep declining until you're asked some security questions instead.) You'll be able to at least try to play without reinstalling anything.
You won't have an Options.ini until you try to open the game for the first time, but after that, you can edit it to force windowed mode again.
If that doesn't work either, please look for new errors in the Reliability Monitor. Click Windows key-R and enter "perfmon /rel" without quotes, and you'll see a chart of errors and updates with a column for each day. Today is on the right.
Look for an error that happened at exactly the time of your most recent attempt to open Sims 3. If you find one, double-click it to see more details, then copy that info and paste it into a reply here. If you don't see a new error, check back in an hour or so—the Reliability Monitor doesn't always update right away.