at (someone's) wit's end

Translations
в полном отчаянии
She was at her wit's end trying to figure out how to fix the problem.
Она была в полном отчаянии, пытаясь понять, как решить проблему.
Definitions
In a state of extreme frustration or anxiety, where one feels they have no more patience or solutions left to cope with a difficult situation.
Words
wit

noun
остроумие