I am doing my engineering final year.I am so sad that my lover was died.I can't do anything.where ever I see he is coming to my vision.I am feeling the pain of hell.I can't express my pain in words.there is no life for me without him.I just can't imagine a second without him.but now he left me alone.

Yes, the pain is unbearable. He left you. It is common to feel a lot besides grief - anger and guilt. Guilt that you didn't prevent it, guilt that you are angry at him for leaving you. Grief that he just isn't here to share life and love with you. I'm so sorry. For a while you can't even take a breath, or get out of bed, or get into bed, nothing is worth doing, and your whole body aches with the weight of elephants on your chest.
One thing I can suggest is to talk to him. Put a picture and some little treasures on a shelf on your bookcase and talk to them. Talk to him as you walk around and go places. Be his eyes and ears, and tell him what you notice and feel and are thinking. Even if you don't really believe that he can hear you, do it anyway. If you want to cry out 'why did you leave me' do that too.
Don't try to 'get back to normal.' Why do you have to? Talk to professors and ask for another semester.
Ask family and friends to take you wherever they are going but to just let you be a lump and no fun and not to try to cheer you up - just be there, for the distraction and hugs and companionship.
The loss will become part of who you will become. You don't expect it to go away and you don't have to (despite what some people will say). The pain lessens and lessens with time. Then you will be a good support for the next person who loses someone.

I was widowed - grief is different from everyone, the grieving process varies. Some people find comfort and peace in talking about their loss. Others simply choke and keep it all bottled in.

For me the first 6 months were terrible. The next 6 were paralyzing.

And Joy is right - it never goes away. On occasion I still stop dead in my tracks, remembering.

You need to fnd what works for you - a group, therapy, being alone, being with people, crying, not crying. It's different for everyone.

Can you talk to his family about your mutual loss? In the midst of my terrible, terrible grief a neighbor came over for coffee and said, "Do you know what I remember most?" and gave me a lot of peace.

It varies - and only time makes it somewhat better. You probably don't believe that. I didn't believe it either, but if the loss would remain as intense as it is in the beginning we'd all go crazy.