Hello seokangjun
Did you create an account to buy this ticket? In this case you can check the order list. Another possibility is that the E-mail address was false. Did you also check your spam folder?
If a technical error occurs, it can take a few days to obtain a refund, be patient. If you cannot wait or you never get a refund, you can call the SBB Contact Center with this number:
+41 51 225 78 56 (24/7, waiting times may occur).
Kind regards
Danhiel