How to get my feelings back and start enjoying everything once more?

I suffer from depersonalization(at least I think I do,haven't had a professional diagnose me).Since the day it started I had no feelings and couldn't enjoy anything.
Before I could smell the spring air and get these weird happy feelings,I could go for a walk in nature and happiness would wash over me.I was a happy and fun person.I loved to hang around,play games and such.I enjoyed everything.Everything was so fun.I always thought I was the happiest person in the world all until that one day I smoked weed.Ever since then I have been emotionless,couldn't enjoy anything and lost all motivation in life.

How to get my old self back?

P.S.Smoked 4 times 6 months ago.Didn't smoke since.

[Roger Gould, M.D.]

that is a very strong and unusual reaction. In this case I would strongly urge that you see a psychiatrist and try to find the right antidepressant that will make a change in your brain chemistry. I am assuming there is no other major life event that is connected to this change. This change could be described as anhedonia and if so it will benefit by psychotropic medications.

[Jaquta]

I think that you should visit a health professional.  A psychiatrist would be best.