I am sorry to hear that. I've lost a few game saves when I was new to the game. It was devastating to say the least. After that I read up on all I could on saving backups of my saved games, households and houses so I wouldn't ever loose them again.
Something that maybe worth trying is to launch the game, create a new Sim and save the game. Go back to the Main Menu and press the Load Game button. Select a saved game. Mouse over or hover over the tiny folder under the game saves information. Like shown in the photo in the post linked below:
Sims 4 - Lost all Saved Game Data
https://answers.ea.com/t5/Technical-Issues-PC/Moved-Sims-4-folder-to-desktop-and-have-now-lost-all-game-data/m-p/7321604#M131867
This hopefully will give you an idea of where the game is saving your saved games.