not for the life of me, etc.

not for the life of (one)

One is/was completely unable (to do something), not matter how much energy one put forth. The lid of this jar won't come off for the life of me. Will you try? He had just met that woman yesterday, but he couldn't for the life of him remember her name.
See also: life, not, of

not for the ˈlife of me, etc.

used for saying that you cannot do something, however hard you try: I can’t for the life of me remember his first name.He couldn’t for the life of him understand why she was so annoyed with him.
See also: life, not, of