Just nice if there was some magic word to say and he'd open his eyes.
If there where, I suspect this forum would not exist. It sounds like you have a lot of work to do in order to repair your relationship with your son. You telling him that you'd rather he be a drunk/druggy instead of a JW will sound to his ears that you'd rather he be a drunk vs "serving the true god." That's almost certainly a large factor in why you've been shut out. JWs don't normally completely shun non-believing family once they're indoctrinated (though there's usually a significant withdraw). For him to completely shut you out of his life he has decided that you hate him and are persecuting him for his stance to (as he sees it) serve god. Unfortunately, you played right into their hands. New JWs are indoctrinated into expecting persecution from family/friends very soon when they start studying. When family/friends learn of their cult involvement, obviously they'll raise objections - and knowing nothing of cult mind control, they play right into the expectation of persecution. Your objection to your son's joining the cult only reinforced the indoctrination by essentially proving their prediction right. You NEED to make amends for hurting him. Write letters, send emails, call or visit, whatever it takes. You CANNOT attack him or his beliefs, only express concern for his completely withdrawing from his family that loves him.
From reading your additional posts, I'm going to restate that you absolutely need to read Steven Hassan's books. There's a lot of information there that will help you to fix the root cause of the problem. It sounds like there's a lot that needs to be repaired before you can even begin to undo his indoctrination. This is going to be a long process and will require a ton of work and patience from you.