I turned up random tick speed to get more trees to grow faster on my flat world and it ended up crashing, I joined on the game again and it was frozen. I could still move but nothing else was or updating. Now whenever I join a different world, it crashes and when I leave the frozen world it also crashes. 

 After going back to 1.14.2 I was able to go on other worlds, but whenever I load up the frozen world it stayed frozen. This is very annoying as It was one of my more used worlds.