Can a hit to the head in a bush crash, affect your speech abilities?

I would suspect that the bus crash did affect your ability to speak. To be in a coma for 14 days is an awfully long time, and it suggests some brain damage may have happened. A psychological essment might help understand what happened, especially if you can get one done by a neuropsychologist--someone who specializes in understanding brain functioning. Unfortunately, an essment like that can cost a couple of thousand dollars.