Lost my Monoa Mask

[Enkidoh]

Seconding Jeeqbit above, according to the listing for it on the Lodestone, it is indeed purchasable from the Calamity Salvager if you happen to discard it, so if it's not showing up, it means you still possess it, but probably have it in your inventory.

Are you checking the 'headgear' section of the Armoury Chest instead of the inventory, or vice versa? (The armoury chest is the section where gear goes into automatically and opens up when you select the character sheet, the actual inventory is something entirelly seperate and gear only goes into that if you have no spaces in the armoury chest left.).

Incidentally, the appearence of the Monoa Mask actually isn't unique, as there are some other head pieces with the same appearence, although those have higher level than what the Monoa Mask is. But it is an alternative if all you want for it is the appearence for glamour (it has no other use in the game after that early main scenario quest so you haven't 'broken' your game if you accidentally lost it, so don't worry.).

Either way, welcome to Eorzea in any event!