Abstract: A mortise and a replacement lock for stores door are provided. The mortise includes a housing; a deadlatch movably disposed within the housing; a drive sleeve configured to be engaged with the spindle and driven by the spindle to rotate in a first direction to drive a drive rod to move; a first reset component; and a second reset component, wherein when a driving force on the spindle is removed, the first reset component disposed on the drive sleeve drives the drive sleeve to rotate in a second direction opposite to the first direction to reset, and the deadlatch extends under an action of the second reset component connected to the deadlatch. In this application, the replacement lock for stores door can conveniently replace the old lock without the need to drill new holes in the door.