want to bash my head "na" wall!
here you'd have to use "w" or "o", not "na" :)
bić (regular) / walić (colloquial) głową w
mur (figurative, meaning to find repetitive, impenetrable obstacles on your way to some goal)
walnąć (colloquial) / uderzyć (regular) głową o
ścianę (rather literally, when you for example accidentally hit your head against a wall).
If you wonder why "wall" translates both to "mur" and "ściana", there was a thread about it a few months ago, you can find it [polishforums.com/genitive_plural_mur_wall-18_25208_0.html]