BEAT ONE'S HEAD AGAINST A WALL

{v. phr.} To struggle uselessly against something that can't be beaten or helped; not succeed after trying very hard. * /Trying to make him change his mind is just beating your head against a wall./

{v. phr.} To struggle uselessly against something that can't be beaten or helped; not succeed after trying very hard. * /Trying to make him change his mind is just beating your head against a wall./