I'm in a similar situation; 18 month old and no words, not mama or dada, ba-ba...nothing. Just grunts, screams, screeches and cries. We read books and I focus on first words books for the little ones, i try my hardest to get him to repeat what I say, but to no avail....he laughs at first then after a few times starts to cry because he just doesn't want to, or as another poster mentioned....can't make the connection??? I dunno.
I googled it last week, a few sites did mention that if a child is a late walker then they'll most likely be a late talker. As long as the other milestones are being met, like eating on his own, making eye contact, communication in other ways, like if we wants something out of reach, he points to it and grunts.... It can be frustrating though, I wish I could get just a yes or no answer sometimes, even a head shake or nod....but nothing.... :unsure: