I had a motorcycle accident around three and hafl years ago. I lost consciousness for nine days. After gaining consciousness, I have experienced three major problems:

1- Loss of smell

2- Both my right hand and right leg can hardly work, my leg becomes heavy when I walk and my hand can hardly write.

3- I have lost a lot of vocabularies in all three languages I can speak.

So, I am seeking some advices on how to solve this problem.

Hello khma. How are you? I'm not sure how much I can offer you here, I am not a qualified physician by any means. I can't give you anything approaching an official hypothesis of what the eventual prognosis might be. But, what I can likely tell you... It is evident you suffered considerable trauma to the occipital (rear) and left portions of your skull. Your loss of smell would have been caused by trauma to the rear of your brain. Unfortunately that may be more or less permanent from my understanding. Your loss of vocabulary would be caused by your left brain injury, likely damage to the left frontal lobe. Though there may be damage to portions of your left frontal brain, from what I know through what I've read, the right side of your brain should be capable of taking over the lost functions of the left. This would take time as it would be essentially, to a large extent, a relearning process. Though I believe it is wholly possible from what I've read in the past. As your left brain would also control the right hemishpehere of your body, your lack of mobility in your arm and leg are likely related to this injury as well. Though there is always a slight possibility that it could something simpler such as a nerve compression by the cervical (upper) spine. If the neuropathy in the right side of your body is in fact due to your brain injury, I'm really not at all sure what the prognosis could possibly be for regaining function. If in the best case scenario it is a simple spinal compression, you could likely stand to regain some function. Beyond that I couldn't really tell you much more.
I would recommend seeing a neurologist for your general condition. He might in turn refer you to a speech pathologist to aid in trying to recover your vocabularies, and a physical therapist and/or chiropractor if in fact he or she determines your mobility problems originate in your spine and there isn't extensive or irreparable damage.
Sorry I can't be of more help. Good luck. Hopefully someone here has some more knowledge and official expertise in this area.