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How to Fix a Door Lock That Won’t Lock in Just 3 Steps

Fact checked by Teddy B.Miller

how to fix a door lock that won't lock

Want to learn how to fix a door lock that won’t lock? Check if the strike plate and the latch are aligned. If not, open up the strike plate a little or adjust it by hammering a piece of wood to it. If it does not solve the problem, you have to reattach the strike plate.

If your lock malfunctions in the middle of the night, your only solution is to have a quick fix and replace it by tomorrow if needed. This tutorial will guide you to temporarily lock your door and have a good night’s sleep.

What You Need

Before starting, you need to have all items necessary to fix the door lock. These items are easy to find. You can find them inside your toolbox, or you can make them online or at the nearest local store.

1. Lipstick and masking tape

You will need unused lipstick for the lipstick test. Its color must be bright red to be easily seen once it is marked on the masking tape. In case you don’t have any lipstick, you can use paint or chalk as an alternative.

Aside from lipstick, you will also need masking tape. A white basic masking tape will do. Its length is 0.7 inches by 180 feet once you unroll it. It is typically made of crepe paper, and it tears easily. It will help if the chosen masking tape does not leave a mark or residue on the surface.

2. Screwdriver

The screwdriver will depend on the type of screws that the strike plate has. If it is a Philipps screwdriver, you can pick size #0 if the screw sizes are 0 and 1. However, choose #1 if the screw sizes range from 2, 3, and 4. You can choose a 4-inch shaft for a more comfortable grip.

If they are slotted screws, you can use a flat-head screwdriver. The sizes that you can choose from are 3/32 by 1 ½, 3/16 by 1 ½, and ⅛ by 4. The first number is the width of the screwdriver, while the second number is its length.

3. Chisel, metal file, hammer, and a piece of wood (optional)

These items are only needed if the other methods don’t work. You can use a sturdy metal file that can open the strike plate a little. For the hammer, an 8-ounce to 2-pound ball-peen will do the work. The wood, on the other hand, should be small enough to fit the strike plate.

To make a mortise hole, a chisel is necessary. You can purchase a set if you are not sure what size of the chisel will work for your door. The available sizes are 6 mm, 10 mm, 12 mm, 16 mm, 20 mm, and 25 mm.

What to Do


Step 1: Conduct a lipstick test to check if the strike plate and the latch are aligned

Open the door and place a masking tape on the strike plate. Once done, smear lipstick to the latch. As you close the door, make sure to turn the knob so that the latch retract. Release the knob as the latch touches the masking tape, making a red mark on it. Now, check if the strike plate and the latch are aligned.

Step 2: Open up the strike plate a little or adjust it by hammering a piece of wood to it

If there is a misalignment, it might be because the strike plate is too low or too high. Some of the adjustments you can apply are putting a small wood on the strike plate and hammering it upward or downward to position the plate properly or you can also open up the strike plate a little using a metal file to make room for the latch.

Step 3: Reattach the strike plate

In case you find the door lock not working, the last option available is to reattach the strike plate. Remove the screws using a screwdriver then create a mortise hole using a chisel. Attach the strike plate and secure it with screws. Make sure that you have the right alignment to prevent any inconvenience in the future.

Frequently Asked Questions

Why can’t I lock my door?

There are different reasons why your door doesn’t unlock:

  • The screws in the door hinges are loosening
  • The strike plate is moving out of the position
  • The door itself is shrinking or expanding caused by weather conditions
  • The keys are broken and stuck

What are other solutions available in case I cannot fix it?

You can use a door barricade, motion sensor security camera, or motion sensor alarm system until you can fix your door lock or have others fix it for you. You can find some of these in a hardware store.


Have you solved your problem by following our tutorial on how to fix a door lock that won’t lock? We don’t know when this kind of incident will happen, so this lifehack is very handy, especially if you have no one to call to help you fix the door. It is better to be safe than sorry.

To help others, you are free to share this post with your friends who have trouble locking their doors. We also want to know your suggestions on how to fix a door knob that won’t lock. Just leave a comment below.

Read more: How to fix a loose door knob?

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