There currently is no fix for that other than reloading the save. Due to Whimpy being a neutral ai, you cant take off or add blocks, other than ones specified by the game. I suggest trying to find an old save file and if you can't, oh well... I guess that you are going to have to reset the world.
Also, please refrain from posting threads like this on the rambling section. This type of post should go into the community help section of the forums.