Look if there is tongue tie beneath the tongue if so get it operated. I had a case where every thing was normal but baby never talked. I got her ear tested and it was found she was impaired of hearing. Hearing aid
helped her and now she is perfectly fine. If all this is fine then there is a herb which we call as vach. Just a ppinch [ very little quantity ] of this herb is mixed in a spoon of honey and applied as paste over tongue.