They told him of relatives who had had one or two strokes and had still made a complete recovery. Each day there will be small improvements as you retrain your brain to control your muscles. There was nothing wrong with your muscles but if they are not used they will deteriorate and weaken. The brain made new connections and circuits to enable him to regain many of the lost functions. It takes time and only by practising and practising does the brain learn what new connections to make.
Nerves have to grow and make new connections and new parts of the brain become involved.