Masha-Allah.
Don't day-dream about him. And keep your gaze low.
Most of all, make dua for him that Allah guides him. But remember, Allah guides only those whom HE wills, so if your prayer is not answered in the manner you expect, don't be taking it badly ok?
I understand that sometimes we feel attracted to members of the opposite sex, for various reasons. Some of them are physical, some not - whatever the case is, you should not let it be known that you like him openly, even to your most trusted friends and confidantes. Keep that between you and Allah only.
Be invisible to this guy, and you will become invisible to him too. What I mean is, avoid him wherever you can. Even if you don't talk to him, when eyes meet, they can speak volumes. I'm sure you understand what I mean.
Scimi