I'm sorry that is happening. It usually occurs if you had a poor connection to the internet. If you are playing on a mobile device, log out of the game. Force close the game. Shut down your device for 30 seconds, then restart. Log back into the game. Hopefully you can now begin at level 578!
If that doesn't work, or if you are playing on Windows, please respond here and we will do some further trouble shooting.Β