Abject,
At some point or another we all face these moments where we wonder about what is that that we are doing here.
But this is normally related to something you are going through whether you know or not. It's a phase and I believe it will pass.
Don't be hard on yourself right now, everyone wonders about his or hers own potential. Famous actors, wise doctors.
If you don't question ourselves we feel we don't evolve, this is all meant to say it's okay to be who you are.
If there is anyone that can change that, you!
You don't have to do this alone, you can search for friends, family or even therapy.
We can't simply give up. We must go on and so are you!
Good luck man!