This is definitely a benefit of servers with some sort of death management plugin- either lets you keep your stuff, or sometimes lets you use /back to get to your death spot. truly a great boon when its there
The best way to find your items is reis minimap but if you didnt have while you died, then the best way for you is through cheats. If you havent turned on your cheats on the world, connect your world to lan and turn on cheats then go to "/gamemode 3" (spectator). This way, you can pass through walls and is much better then creative mode when trying to find one. ALSO, do not abuse the cheats too much, itl ruin the game.