sorry to hear of kitties injuries, they are so tiny it doesn't take much to hurt their tiny little heads...:(
I will give you a link to another kitten that had a similar injury recently and you can read on is progress...and perhaps try sending a message to that poster.
it takes time...and patience basically also you have to be looking after his basics needs for him right now as he is pretty frightened an confused by what is going on too.
you'll need to help him clean himself until he remembers how and you'll have to assist feed him until he feels well enough to eat on his own...he MUST get some nourishment, try getting some very soft canned food and making it really liquidy...so he drinks it like his water...or give him a bit by a dropper....he MUST EAT or he will fade away very fast and its not always safe to be 'forcing' food in them not right now....do so with a dropper only.
move him around abit so he doesn't just lay in one spot...try to turn him often and gently move his limbs for him...very gently. other that getting some food into him with a dropper or as a drink and helping him with clean up issues you just have to be very patient and wait and see what he'll regain....he maybe blind, but this may not be permanent...its all wait and see.
heres the link, I will also give you one on how to assist feed, post again if we can help more...♥
http://www.medhelp.org/posts/Cats/Possible-head-trauma-or-concussion/show/1751963?personal_page_id=861539
http://www.medhelp.org/health_pages/Pets/Syringe--Force-feeding-for-cats--Part-one/show/491?cid=2
this one is a video on HOW TO ASSIST FEED A CAT..you will have to copy and paste this one...
http://www.youtube.com/watch?v=U6o17wH6ujk