Disapear a map's section cubes.

It has bugged the minecraft game in which he wore over 250,000 cubes. basically in a particular area of the map is missing a section of land and you can not put blocks in it. This section extends in the Y axis and shaped so that there is a huge gap in the soil below the square that all ends of the ground.
Also, if I move flying, the game stops loading mapping and reaches the point where the map appears showing themselves halved only the originally loaded.
Could you fix the game? Please carry myself working too many hours on that map and frankly if I lose it would be traumatic.
The rest of the games and the game work properly.
Contact me please and I send the map to see if you are sorting it out, please, I beg you with all my heart.