I play on mac and there's a problem with my .minecraft folders, ever since i restarted my computer a while ago all of my worlds on minecraft got deleted and if i added a change to my .minecraft folder nothing would happens.

For example; Ever since the incident, every time i create a world, it doesn't appear in my saves folder in the .minecraft folder. 

I researched to see how i would be able to fix this but none of the sources would help.