You can use the undelete feature to restore a deleted World of Warcraft® character once every 7 days

Information about recovering the Shadowforged Key.

It is not possible to restore deleted or dropped items in Diablo II: Resurrected

Sealed Chest items are unique and duplicates cannot be looted by players.

Information about this sword's unique mechanic

Information on the errors received when restoring a Death Knight in Wrath of the Lich King Classic.

Information on restorations for Diablo III.

If you do not have the faceless mask quest starting item, you will not be able to complete the quests. You may need to abandon the quest to re-acquire the mask.

What to do if the item is no longer in a character's inventory in WoW Classic.

Once a gem is placed into a socket, it cannot be removed or restored.