Minecraft items missing

Okay so today I was playing my minecraft and I was fighting a few enderman in the end when I died I immediately go to where I died which only took 20 seconds to get back to the spot I had died at and all my stuff was missing so I decided to go on the copy of the same word so I would have my stuff back I was just rebuilding everything I had built today and I saved and quit 45ish minutes later I decided to get back on and when I spawn into the world all my valuable items and a extremely valuable diamond sword and pickaxe are missing from my inventory as well as everything else
How do I get my stuff back?