Hello wingwings
If I understand you correctly, you bought tickets and not only seat reservations. Seat reservations are not refundable.
I you bought tickets, you can try to obtain a refund on the SBB site, you will be informed if it is not possible.
You have to give a proof that you din’t use these tickets, for example a copy of your Eurail Passes for the same day and the same persons. It could be a problem if you have flexi passes on your smartphone, I don’t think that it is possible to show again expired tickets.
If you are currently in Switzerland, you could also visit a ticket office.
Kind Regards
Danhiel