My son was delayed in speaking and his says many single or 2-3 word sentences just not a whole conversation, what can I do

Have you been working with him yourself or have you taken him somewhere to get help. Need more information. If you are working with him on your own and don't see much improvement take him to a quality early learning center and they can help refer you to specialists that he may need. It is a law in the US (assuming that's where you live) that any child can not be excluded from a daycare or early learning center or preschool and the people who work there also work in conjunction with various specialists who deal with children who have delays or disabilities or diseases. If your goes to the school and they think there is a problem, they will ask you if they can bring a specialist in and with your consent they will observe your child and from there if a diagnosis needs to be made, they make it and they come up with an IFSP or IEP depending on the age of your child. This will help him because the IEP travels with him all through school and teachers, parents and specialists work together in meeting goals for the child. All of these services are free under a law called PL190-42. Hope I helped... provide more info if you can, I can give a much better answer then.