LinzeeLove It sounds like your save was corrupt, but only recently, and loading a backup save fixed it. I'd keep the backup on hand in case you need it again, especially if you're going to add mods back.
In general, this is the kind of issue that can be a one-off or a recurring problem, and the only way to find out is to keep playing.
The next time you can't load the save, even with no mods or custom content present, delete any lastexception files you see in Documents > Electronic Arts > The Sims 4, then try again to load a save and look for a new LE. If you find it, open it and delete its first line, then attach it to a post here.
Your dxdiag doesn't show much of note, although the Nvidia graphics driver is old and should be updated. You can use the Game Ready Driver here:
https://www.nvidia.com/en-us/drivers/
Run the installer as an admin: right-click the download and select "Run as administrator." Restart your computer afterwards and before trying to play.