world rebooted

In a flat world where I'm building cities. I am using an app, MCPE, so as not to struggle with building mansions and roads. Well, today in that app I downloaded a road and a big house 3 times in my world. Well, I realized that in my world that caused holes in the ground and apparently erased the whole world (all the buildings on the map). Please help me, what can I do to get all my map back???