AT WITS END

{adj. phr.} Having no ideas as to how to meet a difficulty or solve a problem; feeling puzzled after having used up all of your ideas or resources; not knowing what to do; puzzled. * /He had approached every friend and acquaintance for help in vain, and now he was at his wit's end./ * /The designer was at his wit's end: he had tried out wings of many different kinds but none would fly./ Compare: AT A LOSS, END OF ONE'S ROPE.