How to backup The Sims 4?

Hi all,

Recently, I lost my entire Sims 4 game. The reason for this is still unclear; fortunately, after a few restarts, it came back.

Just to be safe, I'd like to backup the game; I've seen several articles on how to do this, but I'm worried to try anything as I'm unsure in case I lose my progress again.

Any help would be greatly appreciated.

Molly