Minecraft worlds deleting :(

I have noticed this bug for a long time now, i thought it would fix itself, i thought maybe it was my xbox, Well it wasn't. Opening a world a closing it 3 three times three times! the xbox will shut of and upon turning it back on, the minecraft world will be gone without a trace. I have done this four times now!! Please help find a way to fix this i am very confused and frustrated please if anyone else has this problem and had fixed it please tell if not please get mojang's attention! Thank you.