Verified answer

just call him, its okay to seem a little desperate it show that your interested in him. dont call him to much. just one or two calls would be find. keep him think mhm why is she calling me? does she like me? and when you do ask him to hangout. he would be thinking mhm cool she seems nice. blah blah blah

I would contact him via email. Just drop a little note ask how he is doing and invite him for coffee or drinks to catch up. Make it light hearted and no big deal. If he doesn't respond then he isn't interested and no big deal. That way he doesn't feel pressure by a face-face or phone invite. I say that since you don't seem to know how he feels about you.

Find his email address and say that you thought you email him and say hello, if he replies ask if he would like to go out to dinner or for drinks sometime. You can do that without looking crazy. Also, if he isn't interested he just won't write back and it won't be so embarassing. Good Luck

Call him, tell him you were thinking of him and you wanted to know how's he's been. Ask him to coffee for a catch up session and let it all begin. Good Luck

Dont's call like everyday, beause it might seem desperate.

If he doesdnt pick up just leave a message, and be casual and ask him if wanted to just talk and hang out.

I hope it goes well.

why do you assume you'll look crazy? just call him up and say, hey, wanna chill? and if he says no, move on...