It's called 'depression' and this isn't the place to get help. Find a mental health professional and do it soon!
Best answer so far, which I subscribe.
DEPRESSION happens to many people in western society and you should talk to a professional about it.
Untreated depression tends to get worse, one danger are suicidal tendencies.
Start by talking to your parents about it, seek a psychologist afterwards.
There is no shame in getting help and treatment can vary from a simple series of talks to some drugs.
Life is wonderful when we are feeling OK.
But if one is depressed AND smart enough, it is easy to figure out how pointless life is: we will die anyway, so why bother?
Well, because along the journey, there are some amazing occasions, that make it all worthwile.
Again, seek help, only if out of respect for your parents, who care about you.
Regards,
Vitor