Push button locks are commonly found on bathroom door handles and other doors in a house that are not exposed to the outside. Unlocking a door that has been closed with a push button lock does not require a call to a locksmith or disassembling the door know--a few common household items will disengage the lock. There are three different procedures to follow--depending upon the type of hole on the front of the door know--and each is straightforward and will not damage the lock.
Straighten out a paper clip with your fingers. Insert an end of the paper clip into the hole in the centre of the door knob. Push the end of the paper clip left and right while holding the door knob steady. Remove the paper clip when a "click" is heard that signifies the push button is now released. Turn the door knob to open the door.
Hold the doorknob with one hand. Hold the hair pin in the other hand. Insert the hair pin into the key slot on the centre of the door knob. Twist the hair pin clockwise until a "click" is heard. Remove the hair pin. Turn the door knob to open the door.
Insert the tip of the flat-edged jeweller's screwdriver into the seam between the edge of the door and the door lock plate. Move the tip of the flat-edged jeweller's screwdriver up and down until a "click" is heard. Remove the flat-edged jeweller's screwdriver. Turn the door knob to open the door.
Unlocking a door that is not your property can get you arrested.