qinshihuang

The video (I can't upload it exactly, so I show it by this link)

I am also facing this problem. Here is the video of how it happened. ( I can try again in hardcore because I copied my world. Although there are many mistakes for this time :(

My world usually storage at application. When I change it to external, the world can't be found in the folder. It is empty. Also, I don't use any resource packs.