Gather a replacement lock, screwdriver, tape measure, and any included screws or keys
Open the door and keep it stable
Remove the screws from the interior lock faceplate
Pull out the interior and exterior lock parts
Remove the latch from the door edge by unscrewing it
Measure the backset and check that the new lock matches the door
Insert the new latch into the door edge
Secure the latch with screws
Install the exterior lock half through the door
Align and attach the interior lock half
Tighten all screws evenly
Test the key and thumb turn to confirm smooth operation
Adjust the strike plate on the door frame if the latch does not catch properly
Tighten everything once the lock works correctly