Many parents and babysitters have faced the scary situation of a 3-year-old locked in a bedroom. One minute she's playing quietly and the next she's locking the door and locking you out. This doesn't have to be a panic situation, even if you haven't seen your bedroom door key in years. Most indoor knobs have very simple mechanisms designed with just this situation in mind and will let you into the room in just a moment.
Look at the centre of your doorknob. If there is a small hole in the centre of the knob, get a paper clip. Open the paper clip up to create a straight stick. Push the straightened paper clip straight into the centre of the hole in the doorknob while turning the knob. The paper clip will push in the release mechanism, unlocking the door.
Slip the head of a thin screwdriver into the slot in your bedroom doorknob if the knob looks as though it requires a key. Turn the screwdriver to the left to unlock the door mechanism. This type of door lock is for privacy rather than security and will open readily with any thin object in the key slot, like a screwdriver, a butter knife or even a coin.
Remove the door knob if there are no openings at all in your knob. Use a Phillips-head screwdriver to remove the screws that hold the knob. Remove the knob and reach into the hole in the door. You will easily be able to remove the bolt that connects the knob to the hole in the strike plate and open the door. Replace the door knob pieces in the exact order that you removed them.