I have Minecraft PE. I made a cool world with good items and a nice house. I had to leave for school, but when I got home I got on my tablet and played Minecraft, my world was not there. Now every time I make a world and get off Minecraft, it is not there. What do I do?
You need to make sure that you press "Save and quit" and the properly close out the application.
If you are on an android, press the back button until it asks you if you want to quit. If you are on an iOS device, double tap the home button, press and hold the Minecraft PE icon and then press the red X.