My son was stuck in single player mode on one of his worlds.
Black area appeared yesterday in the meadow. He had come in and since it was blocked with impossibilitéd out of the area. It was unfortunately saved.

Commands no longer met or very rarely.
From time to time we fell with bats flying around, then revienait t the top of the area can not come out.
We could not die even when changing mode, the night never fell.

I tried to change the texture, install java 64 bit, nothing worked.
I managed to teleport cheat + LAN mode but when I sauvegardais, I returned to the area of ​​the black hole.
I managed to save by dying but by the character relogguant the major part of his world disappeared into a black hole. It only remains an area around the main house.
And almost reaches to open the chests.
I hope you can do something to save his world.
Thank you in advance for your help.