Quokka_003
I think you mean your saves are not loading, not that your saved worlds have disappeared?
Open Terminal (Applications > Utilities) and open the Terminal app. Copy/paste this command at the prompt and hit Enter/Return.
find ~ -type d -name "*saves*" 2>/dev/null
It will search your Mac user account for a "saves" folder and will take a while. Leave it to do its thing and make sure to allow access when the OS prompts you for permission for Terminal to search various locations. The command prompt will reappear when it is finished. Please copy/paste the results here.