I have no idea where my keys are.
have no idea
idiomto not know something at all; you use this when you are completely unsure about a fact or a situation.
When the teacher asked about the complex math problem, the entire class admitted they had no idea how to solve it.
Despite his years of experience in the field, he confessed he had no idea why the system failed so suddenly during the final presentation.
Last updated April 22, 2026