Southwest does not provide refunds for travel cancelled for COVID reasons unless the original ticket was refundable (not a Wanna Get Away fare).
According to SW guidelines, if you decide not to travel, you must cancel prior to 10 minutes before departure in order to receive Travel Funds for future use (for the value of what you paid). Generally, travel funds expire one year from the date of purchase of the original flights. That said, there were some Coronavirus exceptions that extended the expiration to 2022 in certain cases.
IF you did actually cancel you travel (and didn't simply no-show), you would have received a cancellation notice via email with the travel fund info, including expiration. You can also generally find travel fund info in your Southwest account. IF you did not cancel the travel and just no-showed, you are, unfortunately, out of luck.
Find out more about travel funds here and here.
-A List, Companion Pass holder
