Saul should have wiped out the Amalekites, and because he failed to do so, they were free to raid David’s camp, take his family, and the families of his men, including all their stuff.
Then David found a man whom the Amalekites had abandoned, and David used this man to show where the camp of the Amalekites was located,
“And when he had brought him down, there they were, spread out over all the land, eating and drinking and dancing, because of all the great spoil which they had taken from the land of the Philistines and from the land of Judah. Then David attacked them from twilight until the evening of the next day. Not a man of them escaped, except four hundred young men who rode on camels and fled” (1 Samuel 30:16-17).
Thus, David recovered all the families and all their stuff. What does your zeal for the Lord move you to do?