What should I do about one of my friends no longer talking to me?

One day a few months back nearly a full year, one of the two very close friends I have decided he would cut off my other friend and I. We’ve all mutually known each other since elementary school. We are now juniors in college. I know, I’m a dude, I’m not supposed to get all worked up over stuff, but I thought this man a brother to me. We went though all the phases and fads together. I can honestly say I love this man like family (same goes for my other remaining friend). Despite our childhoods consisting nearly entirely of being around each other, he just blocked us on social media after months of cryptic nonsense and dancing around our questions. From what we’ve heard he’s taken on a new personality and it hanging around with people he and the rest of our group were never very fond of. My friend and I are nearly clueless as to why he seems cryptically angry with us and has taken on this new social life. We miss our friend and we’re both worried about him, but whenever we try to talk to him he rejects us and replies with the same cryptic bull as before. Should we just forget about him? (It’s impossible, half of everything we say is an inside joke between the 3 of us). Should we keep pestering him? Should we leave him alone for a while? Our parents know each other to a limited extent, should we try to get them involved? I miss my friend. Any advice would be appreciated.