Destoryed all my building

So yesterday i tried signing back into my world because it just like logged me out of minecraft, and when i joined back to that same world all my things were gone and it spawned me in the original spawn. When i went back to where all my building were and all the building where gone and there’s just a huge whole where my buildings were. I reset minecraft and my phone but it’s still gone and i don’t know why it happened.