When I am in survival it will delete everything in my inventory after I leave and get back online

I was playing like normal I get a few diamond and that kind of stuff I get off to go to bed. A few days later I decide to get back on and all of my inventory, levels, armour, and offhand were completely gone. I tried loading it up a few times and it never came back, I checked all my chests and I was sure it did not get killed.