iPKMiX I've merged your post with a longer thread about this issue. Did you add -dx9 as a command within Steam? I wrote out how to do it above:
For a Steam install, open Steam, right-click Sims 4, select Properties > General, and add -dx9 to the Launch Options box.
I ask because that almost always fixes the issue in Windows 7.
If you're sure you've added the command correctly, and it saved (please double-check), and that still isn't helping, 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 4. 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.
avisub I've merged your post as well. Please see the section of the first post that covers N versions of Windows, which you're running.
