My husband had sole custody of his daughter from age 3-12 and the child went back to live with her mother and within a month he was placed on child support. Is it possible for him to receive back child support, If so what does he need to do.

Did he ever have a child support order? If so, yes, any unpaid support is still "collectable" in the sense that it would be deducted from what ever he has to pay. However, if he never went to court to get an order for support then no support is owed to him.