Looking for a passage in the Old Testament There's this person who prays and begs God to kill him but instead an angel comes and gives him water or something like that. I think it's in one of the first readings from April to July 2015, but I couldn't find it.
You are probably thinking of Elijah, as recounted in 1 Kings 19. It occurs right after Elijah's 'competition' with the prophets of Baal, and also includes the "still small voice" of God.

The Catholic Church prescribes this passage, 1 Kings 19:4&ndash;8, as the first reading for the 19th Sunday in Ordinary Time, Cycle B, which in 2015 fell on August 9th&mdash;you were nearly, but not quite, correct in identifying the date.