When game was accidentally closed while friend picked up his items after dying, he didn't have them after rejoining world

Me and my friend were killing blazes at a nether fortress but a ghast killed my friend. So he came back quickly while I watched his stuff. But when I tried to give him his diamond sword back, I accidentally moved my mouse too far and closed Minecraft (NOT THE WORLD, MINECRAFT ITSELF). When he joined my world once I reopened Minecraft and joined, his levels were there but all his stuff was gone.