You need to look at your fare rules very carefully as well as the applicable CoC. Some airlines have policies of refunding nonrefundable tickets or allowing changes that otherwise wouldn't be allowed if the passenger has applied for a visa (in time) and has been denied; you need documentation of the denial.

Nonrefundable often means changeable with a fee, so you essentially get an airline voucher to use later minus a change fee typically in the $250-500 range. The voucher might need to be used in the same of higher fare class, for an international ticket, for a more expensive ticket, for the same route/region, etc.

If you have EF, you should be able to find your fare rules from the fare codes on your receipt, assuming that priceline used a published fare. Your receipt looks like you might have a broken fare and the /CH and /IN designators make me suspect that these portions are special bulk or consolidator fares, which would have their own rules.