Some doorknob designs and configurations are more practical than others. Just ask anyone who has ever found himself accidentally locked out of a pantry or bedroom with no practical way to open the lock from the outside. Fortunately, normal household bedroom locks aren't difficult to penetrate and you should be able to get back into your locked room with some basic household items. Use caution when trying to unlock doors and call a locksmith immediately if someone could be in danger due to the locked door.
Plastic Card Method
Step 1: Hold the Doorknob
Grasp the doorknob firmly in your nondominant hand. If you are right-handed, hold it with your left hand.
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Step 2: Push the Door
Push the door so that the gap between the doorframe and the locked door is as wide as possible.
Step 3: Insert the Card
Insert your plastic card into the gap above the doorknob at a slightly downward angle. If the door has trim on it, you may have to remove the trim in order to gain access to the locking mechanism with a plastic card. A pocketknife will also work for prying open a door, but there is an increased risk of damaging the paint around the door or cutting yourself, so the plastic card is a safer method.
Step 4: Wiggle the Card
Gently wiggle the plastic card downward until you encounter the locking mechanism of the doorknob. In your mind, picture the metal piece that protrudes from the door into the doorjamb. It is angled at the end. Plastic cards can break during this process, so use one that you don't care about or use very often. Most store customer rewards cards are easy to replace if you break them.
Step 5: Slide the Card
Slide the plastic card against the angled portion of the metal locking mechanism and push it back out of the doorjamb by applying leverage from the portion of the plastic card that you're holding.
Step 6: Push the Door
Push open the door when you feel the resistance from the lock start to give. You may have to wiggle the card and doorknob to get the right opening and it may take several tries.
Doorknob Removal Method
Step 1: Remove the Knob
Manually remove the doorknob if you can't get the door to pop open using the plastic card. If you have to remove the doorknob with a screwdriver, tiny screwdrivers tend to work the best as they're the easiest to maneuver in the tight space between your doorknob and the screw.
Step 2: Find the Screws
Locate the screws on either side of the doorknob. These are actually holding the doorknob together through the door.
Step 3: Remove the Screws
Use your screwdriver to remove them and then manually pull the locking mechanism back into the door to open the room and unlock the door.
Hinge Removal Method
Step 1: Determine Door Swing Direction
Determine if the door swings toward or away from you. If the door swings toward you, you can remove the door from the hinges.
Step 2: Cut the Paint
Use a razor blade or box knife to slice around any paint that might be holding the hinge pins to the hinges.
Step 3: Position a Screwdriver
Place the tip of the screwdriver directly under the lower hinge pin at an angle.
Step 4: Push Hinge Pin Upward
Tap against the screwdriver hard enough with the hammer, regaining leverage each time, to slowly push the hinge pin up and out of the hinge.
Step 5: Repeat With Upper Door Hinge
Repeat with the upper door hinge, being careful to make sure the door doesn't fall off the hinges and on top of anyone.