Sims 2 players, this is for you. When you update windows, it puts a file in your system that disables all Sims 2 resolution options. You used to be able to just look it up, get the file name and delete it. Problem solved. However, With the newer "Ultimate Sims 2" download, that thread has been closed and deleted. Many players are unable now to get that file name. There is a fix posted. I'll link it. However it says to just do one file, it's not clear whether it's base game or the one you play from. My son helped me with this problem, and we did both of those files and it didn't work. So he did a copy/paste of the first file correction and did the base and all expansion and stuff packs. It is now a functioning game. This link also offers edge smoothing code and shadows code. The three things are all in the same file folder so it's a rinse and repeat. So without further ado here is the link:
https://simscommunity.info/2016/04/27/the-sims-2-setting-up-the-resolution-windowed-mode-smooth-edges-sim-shadows/To make it easier - go to your C drive, Type TSData in the search. All your files will show up in a nice neat row. Edit the first, then copy/paste down the list.