Hi Ilija
I'm sorry you're feeling so unhappy. I also played violin for a long time. do you enjoy playing it, or is it just for your dad?
i know it's not much help right now, but things won't always be this way - the girl you like might still reply to your messages, or in a few days you might start feeling better whether she does reply or not. it's not a promise but it still might happen.
i read this quote by a famous author once, and it was a list of advice he was giving to people in general. one of the things was "you are not as fat (or ugly) as you believe".
hang in there. do you have a teacher at school you like who you could talk to about feeling so depressed?