I Dont understand why ?

be bold and confident (even i you arent at the moment) ask him out, not like a date date but like a hang out time alone at a nice park after school or maybe if you have off campus lunch ask him if you want to get a slice of pizza and well hang talk about stuff maybe that will drift you guys back together and a little closer ;) and even if he says no act very casual and be like "mkay maybe next time" and ask next time!