Q:

Why can't I be happy in the pursuit of Nirvana?

If you are happy, you will have to face sorrow right? So I am being told to just observe everything with equanimity or Anapana. TBH which is very boring So I observed that instead of thinking of everything leads to sorrow in this world, why not enjoy this moment. (Is is necessary to keep observing when you are happy.)   
After all we want Nirvana because we are looking for a being in a state of something eternal, Which is equanimity.
According to me Equanimity is not happiness for sure. 
In this Video Philosopher and writer Jim Holt says  we can't live like dead humans as per Buddhism and think like a western.
I have experienced intoxication occasionally and I was in to Anapana for nearly a week and I have kept myself safe from any kind of intoxication for a year, everything was going smooth breathing while walking, lying, sitting, talking not always but I was satisfied with my pace of being aware.
But this weekend I had nothing to do and suddenly a teeny tiny thought arises which says to get drunk and at the same time one of my friend said the same thing and we get drunk.
I was still trying to figure out what is happening in mind, Why I am feeling different now.
I know I should not be drinking is there anyway I can punish myself. I was actually scared of getting attacked by mind when alone. It attacked.
Should i keep in doing Anapana as i believes that it cuts your Karmic chain for the moment.

A:

If you are happy, you will have to face sorrow right? So I am being told to just observe everything with equanimity or Anapana. TBH which is very boring So I observed that instead of thinking of everything leads to sorrow in this world, why not enjoy this moment. (Is is necessary to keep observing when you are happy.)

To answer this section:
You are temporarily right to try to be happy this moment. A wise person would think "How can I maintain this happiness forever without changing?". A sensible person, upon contemplating the matter for some time, realizes there is nothing created that he or she can retain forever. He or she furthermore realizes such possessions can't be guaranteed to be with oneself beyond death. Thus, a wise person decides the boring path provides freedom from such a mass, sorrow and disappointment.

After all we want Nirvana because we are looking for a being in a
state of something eternal, Which is equanimity
According to me Equanimity is not happiness for sure.

To answer this section:
Eternity is a word used to describe something that was created and lasts for ever. Nirvana isn't such a thing that is created. Nirvana has not been described as equanimity in the Tipitaka to my knowledge.

I have experienced intoxication occasionally and I was in to Anapana
for nearly a week and I have kept myself safe from any kind of
intoxication for a year, everything was going smooth breathing while
walking, lying, sitting, talking not always but I was satisfied with
my pace of being aware.
But this weekend I had nothing to do and suddenly a teeny tiny thought
arises which says to get drunk and at the same time one of my friend
said the same thing and we get drunk.
I was still trying to figure out what is happening in mind, Why I am
feeling different now.

To answer this section:
Where is that thought now? Did it come to your mind out of your own will? Can you control it? If you can't control it, is it suitable to think the thought is me, mine, or my soul?

I know I should not be drinking is there anyway I can punish myself. I
was actually scared of getting attacked by mind when alone. It
attacked.

To answer this section:
I suggest your reward yourself by contemplating the benefits of avoiding drinking rather than punishing yourself. I'm sure there's plenty online resources to explain these benefits apart from a Buddhist context.

Should i keep in doing Anapana as i believes that it cuts your Karmic
chain for the moment.

To answer this section:
False. If a person can cut the karmic chain for a moment as such and dies, he'll attain Nirvana. There is no moment a lay person is void of Karmic chain (sankhara). This is what binds us to bhava (world, so to speak).
I suggest your practice Satipattana Meditating which includes Anapana Sathi and extends a more insightful consciousness to day to day activity.
Buddha has asked us (citation needed) to travel in the Noble Eightfold Path even if it means crying along the way. Why Buddha says so is because he knows, and intelligent people understand that if someone missed the opportunity to understand the Four Noble Truths, the resultant suffering can be extremely large.
Buddha has said

Nibbanam Paraman Sukhan

Which translates to

Ultimate Luxury is Nibbana

