I've seen an American website named “NamUs Missing Persons” (which is part of the database “National Missing and Unidentified Persons System”) that allows to search for missing people. Anyone can search for a person (I've searched for Betty Ross and no person with this name appears) but, if you register, you can also add data to a case or you can introduce a new person. It seems a good system, they say they have helped resolve 13% of cases.
Internet is full of unresolved cases of missing people, but one of the cases that has drawn my attention is that of a girl who appeared dead in a water tank in a hotel. Her name was Elisa Lam and the curious thing is that the last time she was seen alive was recorded by a security camera in the hotel elevator doing very strange things. Have you seen it? You'll found it in Youtube wit the tittle “Elisa Lam Elevator Surveillance Video - Hotel Cecil”. It has more than 2 million views. I recommend that you take a look at the story at Wikipedia (the tittle of the article is “Death of Elisa Lam”), it's really creepy in many ways.
Fortunately, there are also a lot of cases about people that had disappeared and have been found. You can know about some of these cases on the internet, at the article “10 Missing People Who Were Eventually Found Alive Decades Later” by David Hewitt.