My world disappears after I rejoin beta

I joined the beta version few days ago. Loaded my world into the beta without backing up (I know its my bad). Things were fine until I tried to leave beta. Reinstalling the public version and then found that the world cant run in normal version already. 

So I rejoined beta, installed back the beta version. And the world is gone. It doesn't show up in the world selection. I checked the files are still there in phone storage. In fact, when I go back to the public version, it is shown in the world selection (but cant be played as expected)

Please help