draw a blank
Advanced (C1)neutral
Not be able to remember or find something.
"She tried to remember the password but drew a complete blank."
Hear it in context

Lili Reinhart vs. Tom Bateman | Hot Ones Versus
First We Feast · 5:38
The first player to draw a blank or repeat an answer must eat a death wing.

Learn English While Playing Geoguessr with Me! 🗺️🌏
Learn English with Bob the Canadian · 38:17
In English, when you draw a blank, it means like I think I know the answer,

A neuroscientist’s guide to protecting your brain, in 58 minutes | Lisa Genova: Full Interview
Big Think · 27:51
but too much is going to put you in overwhelm and cause you to draw a blank.