Interior doorknobs that lock, such as those found on the bathroom doors in most homes, can be unlocked from the outside. Unlike doorknobs on exterior doors, which feature security locks, the locks for interior doorknobs are merely for privacy. A small hole in the centre of the knob allows access to the knob's internal mechanism, which can be manipulated to unlock it. Doorknobs with a tab lock can be unlocked with a long, thin screwdriver.
Insert the screwdriver into the hole in the centre of the door knob. Hold the screwdriver straight and level.
Insert the screwdriver until it bottoms out, and then rotate the screwdriver slightly until you feel it drop into a slot inside the knob.
Gently rotate the screwdriver a quarter-turn clockwise to rotate the lock tab on the inside doorknob.
For door knobs with a push-button lock, something long and thin such as a straightened paper clip will unlock the knob mechanism. Insert the paper clip into the hole in the knob and press the release button inside the knob.