Why m i not happy in this God's beautiful earth?

I don't know how to explain my situation.Well, I have every luxury in life to stay happy but for some reason m always dejected. I was an average student during my school days. I have few friends but they are the only people in this world which makes me happy.M not a bad person at all.I do not smoke nor do i drink.Few months back i even gave up on non-veg.I m never happy with all the pain and suffering around m.It kills me.I try and devote my time helping others but m still not happy. Every time i keep wondering the very reason of my existence.By God's grace i found a good job but m still not happy.I stay absent, sometimes for days and sometimes i just return home after reaching office.This way i have made a fool of myself in office but i know m not a fool.M just not happy with this life I don't no what m looking for and what do i want.My parents came up with a very decent marriage proposal And the girl also likes me but m concerned about my future.I feel lost and alone even in the crowd.Once i even tried committing suicide but i was rescued by the doctors.WHY M I NOT HAPPY? i hate people who trouble others and brings pain and grief to others.I don't easily mix with people around bcoz i just don't find the right person to b with apart from my friends bcoz they are very nice human beings. I do not hold any grudge towards anyone even who hates m.I pray to God for the well being of my family and others and to give me answers to my question in any way he can.But no result.I feel that m a complete Failure and do not deserve to be here.No matter what pep talk people give m its only for the time being and then i get back to my usual self.I Don't know what to do.Sometimes i just lock my room and sit in complete darkness.It gives m the feeling that m now free with all the restrictions, pain and i do not exist.Plzz anyone has any solution to this problem becoz i have given up on this.I have so much to say but I cannot put it in words.