@eleanxr_dunkin Did you happen to change any graphics settings in-game while a save was loaded, or did you load a save after changing some settings without first quitting to desktop? That's one cause of the white/gray screen. If you're not sure, you can go into Documents\Electronic Arts\The Sims 3 and remove options.ini. The game will spawn a new copy of the file with default settings, which you can change back later if you want; but first load a save and see how it looks.
If that doesn't help, please run a dxdiag and attach it to a post.
https://help.ea.com/en-us/help/pc/how-to-gather-dxdiag-information/
Please also go into Documents\Electronic Arts\The Sims 3, open the file labeled config.log, copy the first 40 lines or so (stop when you get to Options), and paste them into a post here. You can delete your user and machine names (about 25 lines down), but nothing else in that file is specific to you or your computer. Please use a spoiler tag on the text.