Chunks missing in the world

So recently I downloaded Minecraft deluxe edition and started playing but after playing a few days I noticed the game signed me out of my Microsoft account so I easily signed in but the world showed the missing textures picture, so I loaded in and the world was almost how I left it but chunks were missing and the world counted it as part of the terrain so I could basically fall straight through the chunk if I chose to jump in, I lost my house and items because of it so I deleted the game and reinstalled it trying a new world but it still happened. So now I just have one world and I'm afraid to touch it so I've been messing with it on copied saves. Hopefully you can fix this to avoid future issues