Sims 4 saved game deleted after update

@ameliaashdown and @DisneyNurse  It's possible your entire Sims 4 user data folder, including your save files, was uploaded to cloud storage.  If that folder isn't in Documents\Electronic Arts, the game can't find it and will create a new folder with no content.

In Windows, you can try opening a File Explorer window and searching for "config" without quotes.  Each Sims 4 folder that's been used by the game will have exactly one config.log, and that file will have a timestamp from the last time Sims 4 launched will using that folder.  So you'll see a config.log from the most recent time you played (without your old saves), and hopefully another config file in another Sims 4 folder that's from before and does contain your old saves.

If you do happen to find old saves, you can move or copy them into the new Sims 4 folder, as in, the one the game is currently using in Documents\Electronic Arts, and you should be able to play them again.

If it turns out OneDrive is uploading your data to cloud storage, you can disable it entirely, or just tell OneDrive not to sync the contents of Documents.

https://support.office.com/en-us/article/choose-which-onedrive-folders-to-sync-to-your-computer-98b8b011-8b94-419b-aa95-a14ff2415e85