there seems to be a big chunk of the game data gone from the playing area!!

there is a giant block cube missing from the game playing area. i can not get to close but if i had to give a rough estimate it would be 20 x 20 block in perimeter and is roughly about a minimum of 200 blocks deep.

also when i laying down cobble stone on the water to make a farm area the area where i laid down is completely gone and when i try to replace it it will not do anything and it glitches and will not allow me to move when i am on the water near the blocks that i had previously laid.