Chunks of my world deleted themselves.

No matter how many times I closed and reopened minecraft they were still gone, the floor of the house disappeared and my entire mine. The chunks go all the way to the void. It's a survival world as well so it was difficult to investigate but the chunks are random, a mass are missing by my spawn and a few more missing dotted around the area. The chunks havent glitched because when i broke sand they all fell so they're literally not there.