Get out of the bed.

Always finish what you have started, whenever you are playing something or participate in any kind of contest do your best to win, if your chances are small and you can avoid participating then do so. Become good at what you like doing and make sure the others know you are good at it. Praise yoru friends and maybe they'll praise you back. And, yeah, by the way, have as many friends as possible, people being nice to each other is a great confidence booster. Don't worry, because you are young you have time to gain back your confidence. When you accomplish something no matter how small send a message to your friends and let them know. Send a message to me and let me know. I'll be waiting for your message.

Go to a pharmacy and buy some confidence boosters.