The easiest way to report a lost item is by filling out a lost property report online: www.sbb.ch/en/find. On the basis of the incoming found property reports or found objects, you will be informed after 4 and 10 days on the status of your lost property report by text message or e-mail.
You may find further information at www.sbb.ch/en/lostandfound.
Have a nice day.
Greetings, SandrineB