Numbness is purely a reaction to the pain that's in your life, it's a way your mind and body shield themselves from the destructive influence of pain. Unfortunately, as I think you've just realised, this also dims the light of happiness and love that you receive. Numbness shuts down all of your senses and emotions to protect you from anything that hurts, and the worse thing it does is diminish your experience of everything good there is in the world.
The only way past it is to accept the pain, the sorrow, the hurt and the many years of desolation. Also accept the love that's around you, from your parents and from your friends. Acceptance is a very hard thing to do first off, it almost seems like you want the pain, but that's not the case. Acceptance is a way of fully acknowledging and owning your emotions and thoughts. It's a way of saying "I know you are there, I feel you are there. I don't like it, but I'm okay with it, and it will pass."
The best way to practice it is, a few minutes a day, in a controlled space, like your bedroom, just open yourself up to your emotions and just be with them. Let them hang around and don't do anything with them. Don't think about them or act on them, just feel them, experience them, and them let them out. Allow yourself about 10-20 minutes at a time for this, probably about once a day. Then at the end you can shake off what's left, clear out your mind and go back to doing all the stuff you need to do. It's also a good idea to keep something nearby that's positive for you, like a picture of a loved one or friends, as this will help keep you grounded and balance out the negative emotions if you have been numb for a long long time.
The only reason to do this is because on the otherside of acceptance is the happiness and peace that you've been missing all these years. It might seem like you've just been protecting yourself from the pain, but you've also kept out the positive emotions of life, bringing a larger pain that's worse than any other pain there is.
The only thing I can say now is "Good luck."