A door latch consists of a striker and a catch. The striker is the part that resides on the inside of the door and strikes the catch, which is attached to the frame of the door. When the striker connects with the catch, the door latches closed. Latches with strikers and catches can be found on a variety of doors, but they all install in the same basic way. You can purchase new strikers and catches from any home improvement store in a variety of styles. They can be installed in just a few minutes with a screwdriver.
Unscrew the screws that hold the old striker and catch in place. Take the old hardware with you to the store when you buy the new hardware so you can match any remaining hardware.
Install the catch on the door frame as close to where the old one was located as possible. Since the screw holes will probably not line up with the old holes, you do not have to worry about fitting the new screws into old holes. The screws will screw into the frame with just a screwdriver.
Place flour on the catch and close the door to mark where the striker should be placed to line up with the catch.
Install the striker by screwing it into the door where the flour marks are located. As with the catch, you can insert the screws in the wood with just a screwdriver. Make sure that the striker is snug so that it will not move when it hits the catch.
Clean the flour off the catch and test the door. The catch can have small adjustments made to it by loosening or tightening the adjustment screw.