Why didn't he contact Hannah's adoptive mother? Hannah would always keep in touch with her and Richard just needed to tell her mother that he wasn't her brother. She could then tell Hannah and Hannah could return. Not that hard to figure out that's the way to find Hannah.
Why didn't he contact her parents? Or try social media? Sorry, but I found the story absurd. Not consistent. A decent girl meeting a guy in a parking lot accepts a coffee and cake without knowing him, a complete stranger? Good girls don't do that. And without transition, Richard leaves Hannah's home after parting with her; goes to confront his mother and without hesitation says he can't reach Hannah, albeit the narrative indicates he just left her. Ridiculous in this day and age. 👎🏼