David wrote this song while hiding in a cave from King Saul, who was trying to kill him because David had been anointed future king of Israel, and Saul was jealous of David. So Saul chased David all across the land in an attempt to kill him. In short, everything has gone wrong for David, but he did not lose hope, because he trusted the Lord and he trusted that there was a purpose for what he was experiencing as he hid in a cave from Saul