How to make someone up out of a coma?

i know the title may sound silly but I'm 15 boy and my 23 man year old brother got in a motorcycle accident one month ago and basically they didn't think he was going to make it and he has been under sedation for a while now and they stopped it and he was opening his eyes a little and squeezing people's hands but then he had a op to fix his broken elbow so they had to sedate him more which set him back but all the signs show he's improving like breathing on his own etc. so i was wondering if there is anything i could do to try and get him out of his coma which by now is semi comatose (think that's how you spell it) so is there anything i can do i.e playing heavy metal music to him or relaxing music? describing a place to him like heaven or just his house? or maybe even slapping him round the face? any help would be MUCH appreciated :'(