@kreepsymusic I can only imagine how frustrating this is, but it's also probably the root cause of the problem, so if you can get past it, Sims 4 should work again. Please run a couple of basic checks of your Windows system files:
- Hit Windows key-X
- Choose either “PowerShell (Administrator)” or “Windows Terminal (Administrator),” whichever option is offered
- Inside the window that appears, copy and paste “DISM.exe /Online /Cleanup-image /Checkhealth” without quotes, and enter
- If an error is found, stop here and let me know what it says
- Otherwise, hit Windows key-X and choose “PowerShell (Administrator)” or “Windows Terminal (Administrator)”
- Inside the window, copy and paste “DISM.exe /Online /Cleanup-image /Restorehealth” without quotes, and enter
- The system will start validating soon. If it throws an error, please list it here
- After it reaches 100%, hit Windows key-X again and choose “PowerShell (Administrator)” or “Windows Terminal (Administrator)”
- Inside the window, copy and paste “sfc /scannow” without quotes, and enter
- Post the message you receive here
Restart your computer, hit Windows key-i, select Update & Security, and click the box to check for updates. If any install, restart again afterwards.
You didn't mention whether you have a third-party antivirus installed, but if you do, please disable it, temporarily, before trying again to uninstall the runtimes. Make sure nothing else is running on your computer at the same time, not even a browser window.
If that doesn't work, you can try installing the all-in-one runtimes from here:
https://www.sereby.org/site/downloads/All%20in%20One%20Runtimes
(Make sure to click the small Download button at the bottom of the text box, not some larger flashy Download button at the top of the screen. You don't need to donate money.) This is not as reliable as manually uninstalling and reinstalling, but it's easy enough to try.
If this doesn't work either, let me know, and I'll ask someone for a consult.