How often do you remember an old show you loved watching and wonder how the actors are doing so long after the show has ended?Many of you who watched “Little House on the Prairie” and were excited to follow the family’s every move on their farm in Plum Creek,which is close to Walnut Grove, Minnesota, probably would like to know what the performers are doing these days.The gorgeous Melissa Sue Anderson, who played Mary Ingalls,was adored by her fans, who thought she would stay in their lives through television, but she had other ideas.