Most "non-refundable" fares have some value for a year from date of issue, but change fees and fare differences will apply when you use the value. You need to read the rules of the fare that you purchased.
Standard practice is that a no-show for a flight causes the rest of the itinerary to be automatically cancelled. You really should research this in the
Avianca forum. The fact that you paid with points is invisible to the airline. They just see this as a ticket purchased through Expedia.