Problem with Plot Quest for Incense Valley

[vase3a]

Before Heritage update i didn't have any main (plot quest) and got from some mobs <Yanon's Letter>, i though i won't need it and destroyed. After update i got plot quest for Incense valley  << At the end of the song - Meet Again >> to bring Yanon's letter.
Is there any way to trash quest to take again, or to be able to find that letter again? Thx...