Time to head for the mountains and search for your true self
Just kidding. I had been feeling like you for a long time so I can imagine what a devastating and hopeless experience it seems to be. Thumbs up for acknowledging that.
My advice for you is to at first see if there are no medical reasons for all of this. I'm talking about clinical depression. I'm not sure how that would go but someone at you local hospital must know about this.
If this is not the case than as Steve Pavlina would arguably say it's time to say to yourself that you put yourself in this kind of situation. A good psychologist might help a lot with it.
Now that you know how you feel, don't sit and think more about how bad this whole situation looks. I'm pretty sure that you have infinite potential. Good luck