Father lost visitation due to mother going and having it done without a drug test. It was her word against his. How can he get them back?

Mother said she didn't want a drug test done on the father. Only later for the mother to go back and say the father was on drugs. Father lost visitation. Now mother is saying father can see child, but when goes to meet mother and child, mother wont respond and demands money before she will meet the father with the child.