Hello!
To find out if your passes (you mean the Swiss Travel Pass, correct? If yes, you can find all the details here) and, above all, international tickets to and from Milan are refundable, I recommend you take a look at the ticket itself, as the information is usually found there. If you have any questions, you can contact us by phone any time at 0848 44 66 88 (CHF 0.08/min) or +41 51 225 78 56 (if you call from abroad).
I wish you a nice day,
Chiara_S