look blank
To have no emotional articulation in one's expression, usually implying befuddlement, incomprehension, or being overwhelmed by something. The customer service agent just looked blank when I asked how to request a refund. Why does he look blank like that? Does he not remember me?
look blank
Be expressionless, appear dumbstruck or overwhelmed. For example, When I asked her how to get to the hospital, she looked blank. [c. 1700]