Won't Stop Crashing

I have had Minecraft Pocket Edition for some time now, and I occasionaly delete worlds because I think that some of them are useless and take up space, I had tried the Xbox sign up thing now and it worked until one night while charging power went out, I wasn't using my iPad mini and I used my iPad the next day only to see the game crash when the loading screen is done when opening the app, I tried again over and over but it never worked, and if it did load the game would be unresponsive.