I need advice on this boy.?

So, like a lot of people, there's this guy I am head over heels for. The problem is, I don't know what to do. During Christmas time I wrote him this letter saying how I would like to get to know him better, and he did start talking. But, slowly we stopped talking....it's been 2 weeks. He's an easy person to talk to, but is also very shy. I don't want to sound desparate or anything, but I honestly can't stop thinking about him. I would atleast like to know if he is or isn't interested at all. Does anyone have any thought out suggestions of how to start things back up with him again? Please and thank you.