World "deleted"

When I opened up the Minecraft Launcher, it showed I was logged out, so I logged back in. I was going to get back onto my survival world, but it didn't show up on the worlds list. I went into the saves folder where the worlds were kept, and the world file was still in there. I tried taking the world file out, putting it back in, then opening up Minecraft again, but I still didn't see the world. I don't know whether this issue was caused when I got signed out or if it's just a bug where your latest played world doesn't show up.