It did not happen in one day, it took long to be in such a stage where your son is now. It’s better to be calm with ur son, involve someone else to talk with ur son, give ur son love caring, don’t talk harsh, don't abuse him, give him chance to understand, try to find his friend who is better in practicing and request him to help ur son out from drugs and all, in last pray for him
I am very sad to hear this. Inshallah he can make it out of this spiritual rut. I would suggest that you have him watch this show with you and perhaps it will open his eyes.