Hi,please help me?

I'm a 17 year old lad and lately I've been feeling really sad and lonely.I don't know why.Everything around me looks gloomy and depressing and I can't find a way to banish the blues.I sometimes think it'd be better if my life ended.Do you have any suggestions?I think something like a deep poem can help,If you know any good poems for lifing one's spirits please write it for me.thanks alot.