what were the fare rules on the receipt when you bought your ticket? it probably says something to the effect of:
NON-END/-TRAN/-REF/UAONLY
All changes must be made prior to the departure date, or the ticket has no value.
While some refundable tickets allow cancelation after departure, I've yet to see a saver award ticket that does.
PS If you purchased before the merger late last winter, your ticket is more than a year old anyway so even if you had canceled and retained value, it most likely has expired.