I don't know if there is now any television program about missing people, but I remember one that was very famous in Spain. It was called “Quién sabe dónde” (“Who Knows Where”) and presented by Paco Lobaton. It was broadcast in the nineties by the Spanish television (Televisión Española) and had several seasons. I didn't follow it very much, but it was usually the topic of conversation with family, coworkers or friends. I think that it exposed almost three thousand cases of missing people and, thanks to the program, 70% of them were solved.
The most famous case was that of the girls of Alcàsser, a very sad case in which three girls of about fourteen years were kidnapped, raped, tortured and murdered by two common criminals. One of them escaped and has not yet been found.