I'm travelling through my survival world when I bunch on blue shapes start spouting throughout my world. I have had this problem for a short while now, and I can fix it by relogging into the world. Before I can relog, the screen turns into a bunch of yellow and green pixels, but in such a way I can still barely navigate the menus to log out. I  can not successfully quit the entire game, and I have to restart my computer to do so.

When I revisit my world a few moments later, it's completely missing from my world list. I visit my .minecraft folder, check saves, and the world is still there. The world has not been deleted, but it is not appearing in the game itself. It there a way to fix it or get my world back?