"hører" means to hear, while "lytter" is listening. Both hører and lytter make valid sentences but they have different meanings.
drengen ikke lytter?
Lytter ikke. Ikke comes always after the verb.
Could it also be hører instead of lytter?
so,an answer and a question at the same time? :)
Sorry, I don't understand what you mean by that :/
Drengen hører ikke efter . It is also correct. Confirmed by 2 danish persons.