Board Thread:Questions and Answers/@comment-31987252-20170512093145/@comment-28905095-20170512102145

Do you remember what you did before the world crashed the first time? Not that it really matters, but then again if your world is corrupted you should report it https://bugs.mojang.com/. If you know what you did you could also search the bug database at the given location, which in some cases will provide a solution or fix to get around it.

With that being said, I had my worlds crash on me a lot in the 0.15.x series. When a new update came along some started working again, and some crashed. This kept going until 0.16, where now all of my worlds are working again. In other words, your world could potentially become loadable again in the next update.

Part of my issues was related to running MCPE on a really old device, and for some of the worlds it would help to turn down the render distances, and turn of skies (and other demanding graphic stuff). You might want to try this in your world, as well.

A final tip, if you are using any addons (or texture packs) is to remove these before you try to start your world. Along the same line of thought, you could consider changing some of the world settings before loading it. For example to set it to "Peaceful", or even "Creative" (careful with this if you use the world for Achievements), which could trigger something making it loadable again.