this guy I know used to be really social. He was a people-person and pretty popular. but he shut him self down. he's isolated him self from everyone and now has extreme social anxiety. he feels like he can't carry on a conversation in real life. he told me he used to be extroverted and now he's an INFP. I told him that it didn't matter. That introverts are just as amazing as extroverts. but he didn't listen. he's so down on himself and refuses to talk to people even though he wants to, he says he doesn't. he believes there are no perks to being introverted even though I've tried telling him otherwise. i don't know what to do. i don't know him well,(really at all) but I feel bad. i feel like I should help him out....any advice?