My 3 1/2 year old brother did not speaking until now ! He have hearing problems so how to teach him and what are the medical supports are good for him

A child ,any child learns to 'talk' when others talk to him,when he is involved in every day activities,singing songs and playing interactive games will also help.
Reading to him and asking him questions,making it fun and positive encouragment all the time.

Your brother will have the added advantage of knowing a lot about communication as he will have acquired his own way of communicating,he'll need help putting the words to objects,and forming sentances.

The more exposure he has,especially talking to him,will help him come on in leaps and bounds.

As for medical support you will have to speak to your doctor as supports vary from country to country.

He may need hearing aids and speech therapy. If his hearing loss is great enough, or expected to get worse when he's older, then learning sigh language would be a good idea.

What are your parents doing to help him? What country are you in? How great is his hearing loss?