I lost my wallet on a train a few months ago.
Was quite scary, but fortunately, the station staff were helpful (because I reported it immediately): they gave me a slip of paper giving me authority to travel home. Then, when I got back, I filed an online report - and almost immediately, received a phone call telling me it had been found.
It was then delivered to me in the post a few days later (minus some of the money, which I'd used to pay for it to be brought home!)