at a loss, to be

be at a loss

To be uncertain of how to proceed or what to do or think. Your behavior is absolutely unacceptable. I'm at a loss as to what to do with you. Now that the whole schedule has been rearranged, I'm at a loss.
See also: loss

at a loss, to be

To be puzzled or unable to come to a decision. The English clergyman Charles Colton (ca. 1780–1832) wrote, “As completely at a loss as a Dutchman without his pipe, a Frenchman without his mistress, an Italian without his fiddle, or an Englishman without his umbrella” (Lacon, Part 2, no. 116). One may also be at a loss for something, most often at a loss for words, meaning that one is rendered speechless.