Items and xp gone after seconds

I was sitting around when a zombie killed me. I died right in front of my house so it wasnt that bad but i would loose some xp since i had to walk about 10 blocks to my death point i went there and everything was gone no xp, no items no anything, my sibling was on my server but only my sibling. They where lost at the time and didnt pick up my stuff. I looked everywhere in case it fell somewhere or a monster picked it up. Nothing. All my diamond tools and rare blocks gone how do i fix this? I worked so hard 

Edit: i was on normal, then when i explored about 2000 blocks in all directions i changed it to experimental is that an issue? I died in the area that i explored before experimental