beat one's head against the wall, to
beat (one's) head against a/the wall
To attempt continuously and fruitlessly to accomplish some task or achieve some goal that is or seems ultimately hopeless. Some people are never going to agree with you on this, so it's no use beating your head against a wall trying to convince everyone. I feel like I've been beating my head against the wall trying to understand this math equation.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
beat one's head against the wall, to
See run one's head against a brick/stone wall.
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer