what is going through my crushes head?

The guy I like is giving me mixed signals. We used to be really close friends, and he would always tease me jokingly etc, but we have drifted away these past couple of months because we changed classes, were slowly starting to get back to how we used to be. I sometimes see him look at me, but it's mainly me looking at him. We text occasionally mostly me starting the convos. Last week though, he asked to speak to me privately, I said yes and began following behind him (he was quite a bit infront of me). He stopped and started talking to a friend, so I got confused and left (one of his other friends told me to). I felt bad later, so texted and asked him what he wanted to speak about (I didn't get the chance to ask in person). He denied the whole thing though, and said he couldn't remember asking me. I tried just letting it go, but it's making me feel crazy, because I don't believe I imagined it, but I don't want to ask him again because I don't want him to think that I don't trust him. I know that he like someone, because my friend overheard him talking to a mate about liking a girl, he just didn't mention a name. I don't know what to do, and want to know about his feeling towards me.