Lost world when loaded game next day?

I was playing on my world last night and when I was going off I turn off the xbox as usual. When loading up the xbox the next day the world I was working on the night before has completely disappeared, like its deleted but I didn't delete it.  / update 2 hours later. o looked into it and could see that I've got 7 worlds on the top left but if I count my world there is only 6 so its like the system knows there is a world there nut its invisible?