My worlds dosn't show up in minecraft

Hello i'm not sure if this has been sugested before, but i tried to serch it up for about an hour without any result.

The problem i have is that i cant see some of my worlds in minecraft. I og to the .minecraft folder, and there i can clearly see that they still exist. I find this wierd, that the world isn't deleted, but it dosn't show up in minecraft.

I would love if anyone responded to me!
Banansplitt