Yes, you do matter!
What about going to see the school counselor together with your classmate, if you have the occasion to ask her if she'd like it?
Or if you don't want to be direct asking her what's wrong, you could just try to be particularly nice to her, for example asking her 'how are you' in the morning and offering to help if she seems to have troubles with something...also just not having a pen Everything can make the difference.
But really, you matter too Fox