At title menu selected existing world. Clicked on settings. Clicked on creative. Game said no achievements for creative. Immediately clicked back on survival , which is the mode I have been on this map from the beginning, about 10 hours worth. I never loaded the world in creative ,and when I clicked into the world in survival mode my entire inventory was wiped except the armor I had on.This is the third time I've lost items which take hours to acquire and I think I'm done with this game until there is a way to back up or save the world that is built into the game.