Male 18. like a living robot, doesn't talk, doesn't smile or laugh, no facial expression, no motivation. what is this called? how to treat it?

Needs eval in person: This person should see a mental health professional, as there are many possibilities, from medical conditions to several possible psychiatric disorders. It can't be diagnosed by a short description over the internet.

Time to see Psych: It might be depression, or a thought disorder, or early schizophrenia, or drug abuse, or... So he needs to be seen by psychologist for evaluation and possibly then psychiatrist for medication trial to see if he can open up and enjoy his life.