I acquired the quest from the quest kiosk in tower. I did not know what the mementos does neither could i store it away in the vault. I deleted it without knowing what it does. Now when i progress through the quest i can't get it back. Now i cant get the exotic bow nor can i get the mementos or restart the quest from beginning. Now the bow is actually very helpful for current Raid Crota's End. And i am stuck, there is no solution on youtube and no one is actually talking about it. Please do something about it like adding an option to restart the quest or getting the mementos back.