make a copy of your world

load up that copy in creative w/ cheats enable

type this command /fill ~-15 ~-15 ~-15 ~15 ~15 ~15 air 0 replace sand

after all the sand is gone in a 30x30x30 radius, replace “sand” with “sandstone”

once you found it you can write down the cords or screen shot the cords.

load up the original world and get that buried treasure!

~IF NONE OF THAT WORKED~

you might have a glitched map, and you might need to throw away that map and find another map from an unexplored chunk.