Dissapearing chunks

I loaded my creative world in 1.7, i got void particles rising from the ground. I said, okey, i load my world in 1.6.4 and then it may be fixed. I did, and almost half of the map got regenerated, i lost a lots of builds, and i have only one stuff copied out.Pictures attached are showing the middle of my creative field, it was filled with redstone mechanics, and now theres nothing.