I was playing on Zombies just now and i went afk in a spot on firing range that is safe i didnt even take any damage but then when i came back and tryed going to spawn it took me there, immediatley took me back to where i was on firing range and i just randomly saw the night time sky all around me except i could see the zombies and all of my stuff dissapeared, so in panic i disconnected and reconnected so that i could get back to spawn cause i knew that would work to get back to spawn but when i joined i still didnt have my stuff but i still had my levels which makes me think i didn't die. I added a screenshot of my inventory i took a few days (Idk if this will help but may as well try) i dont care about the iron armor that's easily replaceable but the diamond armor is a god set and the sword and bow are both god tools, i dont know if i could get any of this replaced but i may as well try
Maybe you died and no one revive you? When you die, you won't be killed immediately, There's a waiting time for player to revive you. You will lose your stuff after. If you're a donator, you won't lose your stuff.