wool and wood blocks gone and random fire

Put the summary of the bug you're having here
my wool and wood dissapeared
What I expected to happen was...:
for my wool houses to reappear when i reloaded into the world

What actually happened was...:
the wool and wood were gone and after i placed it back, it started a random fire

Steps to Reproduce:
1. unknown
2. ...unknown
3. ...unknown