Hi! Thank you for the response.
Yes, I played it on offline mode the majority of the time. In the beginning I played it offline and kept up with updates for both the game and Origin but I only did so until about 2017 or 2018. I uninstalled Origin, but I did not uninstall my Sims 4 games. I'm not quite sure how to find my game version, but my expansions are City Living, Get to Work, Get Together, Outdoor Retreat, Spa Day, and the Holiday Celebration pack. I do not use any mods or custom content. In the Tray folder, the only items that are there are the ones from the new household I made when I was trying to get my game working a few days ago. The same goes for the saves.
I'll take a look at the troubleshooting tips article. Is there anything else I should do? And thank you so much for your response.
Edit: I just looked at the troubleshooting article and I'm still unsure of what to do since my old files are gone. I never created any backup folders of those files either. I have a feeling I'm out of luck on this. Also, I may have to install the Legacy Edition version of the game. It says I can get it for free, which leads me to believe that I need it due to the message that keeps popping up about it being required for players on older operating systems. But I was able to open The Sims 4 just fine as you already know because that is where I ran into the problems with my missing save files. So I'm not sure if Legacy Edition would be able to help with that if my files are already gone.
Also, I can't restore my PC to another point in time. It shows that I have no restore points. Is there anything else I can do to access my files before the repair? I'm starting to think that the problem was created when I repaired the game without having created a backup folder with a copy of my Sims 4 files. Again, thank you so much for all of your help.