My house and all my builds are gone - except what I have on and in my inventory

It started just as like a square piece missing in my house which usually i'd be fine with and just fix up but this specific part that messed up has all of my chests full of stuff that I've acquired so far. So i was frustrated and logged off but the next day when I logged on i spawned somewhere unfamiliar and my entire house was gone. and not just the house but every change that I made (i lived in a village) and the houses I moved and farms I made and the portal I made where all gone. All i had where the things in my inventory and I don't know how to fix it. I made multiple backups but I don't know how to access them.