Sims 4 background of sims turns black then app closes

@aegisquared  It sounds like you might not have accessed the Startup Repair mode, the recovery mode I mentioned earlier.  Here's a better description:

https://support.microsoft.com/en-us/windows/recovery-options-in-windows-31ce2444-7de3-818c-d626-e3b5a3024da5#bkmk_win11_startup_repair

If that doesn't help, I think you need to get someone to look at the computer in person.  Whether that's a professional or just someone who's good with Windows, this is the kind of problem that needs hands-on help.  It may be that you need to reset the computer or reinstall Windows, either of which would delete your data.  There are ways to grab your essential files first, by creating a bootable USB stick and booting into that rather than your computer's internal drive, but again, that's something that you might need to ask for help with.