If a wizard has the spell, Leomund's Secret Chest, they are supposed to be able to summon the chest by using an action to touch the small replica chest to recall the larger chest.
While the chest remains on the Ethereal Plane, you can use an action and touch the replica to recall the chest. It appears in an unoccupied space on the ground within 5 feet of you. You can send the chest back to the Ethereal Plane by using an action and touching both the chest and the replica. (page 254, PHB)
My question is, is it possible for a wizard to summon the chest if he does not have the spell prepared in his spellbook? The spell only says that the wizard in question needs to be touching the replica to summon the real chest.