Keyboard behaviour change on MBP2011

After install the new version of zorin os lite keys,which at first worked as they should when pressed suddenly don't work unless the 'Fn' button is pressed;sometimes they just make the UI jump to another place like bringing up the items menu of zorin.why is this happening and is this fixable or is there need for yet another fresh install?

I have no idea if this could be helpful or not: