You are still young, you could try exploring different area of interests, there are so much in life to experience. You never know if you stumble upon something or many things that make you feel happy and purposeful in life again.
If nothing seems to work, talk to someone, maybe your parents. If needed, seek professional help.
Sometimes, it could also be the way you view the world that makes you feel the way you feel.
This one, we may not be able to help you unless you help yourself. You have to look inside yourself and find out what happened and how to feel better again.

All the best. Nothing is as bad as it seems. Learn from all your experiences & mistakes. They will eventually lead you somewhere good if you put those lessons to good use.