Don't lose hope; many teens feel that way, hell, even I do! Something thst's helped me (other than damaging my inner ear with loud music) is to not look at past events with bitterness. Life's tough, and it's your right to be pissed and angry, but at the end of the day, you can tune out all the good life brings so that your cynicism becomes a self-fufilling prophecy, or you can have a more balenced view of the world.
anyway, if you want to feel better now, the call up your parents, or friends, or even a help line. Being listened to and having your emotions validated can do wonders, even if they won't objectively change a thing.