I've been playing around
xmodmap to create a custom keyboard (refer to Get the keycode of a key, from a custom made keyboard also).
But now, I can't use the N key anymore, but the Shift+N still works fine.
I think I messed up something, so I performed a reset to defaults of my keyboard (using the Ubuntu system settings).
Now everything seems to work ok, except my N key, my Shift+N key works.
How can I get that key working again?