Inventory vanishing glitch

I was fighting the wither boss and mid way into the battle he was able to kill me. Enraged with this, I left Minecraft without hitting respawn or saving. after I calmed down and went back into my world I saw that all of my items where gone. I am 100% sure my items didn't despawn because I left the second I died and I know the wither didn't blow them up because I left the second I died. I am even more enraged due to the fact that in my inventory I had really good items. For example, the elytra gilders, fully enchanted diamond armor, 4 golden apples, 2 shulker boxes, etc. Plz fix or help me with this.