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Fix a door that will not lock

We'll diagnose why the lock will not engage—strike plate misalignment, bolt binding, key cylinder issues, or hinge sag—and fix it or tell you when to call a pro.

Troubleshooting · Home maintenance
15–30 min
What you'll need
  • Screwdriver (Phillips and flathead)
  • Pencil (to mark bolt position)
  • Graphite lubricant (for lock mechanism)
  • File or chisel (if strike plate hole needs adjustment)
  • Thin cardboard or wood shims (if hinges need adjustment)
Step 1 of 8

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Steps

Goal: Confirm the lock will not engage, then rule out strike plate misalignment before isolating bolt, lock mechanism, or hinge issues.

  • Close the door firmly. Try to lock it with the key or thumb turn.
  • Good: The bolt does not extend, the key will not turn, or the bolt hits the frame—lock fault. Proceed to Check strike plate.
  • Bad: The door will not latch—different problem; see Fix a door that will not latch.

Strike plate alignment

Goal: Align the strike plate so the bolt enters the hole when you turn the key.

  • Look at the strike plate hole and the bolt position when the door is closed. Mark the bolt position on the frame with a pencil.
  • Loosen the strike plate screws. Move the strike plate so the bolt enters the hole. If the hole is too small or in the wrong place, enlarge it with a file or chisel.
  • Tighten the screws. Close the door and turn the key.
  • Good: The bolt extends and clicks into the strike plate—done.
  • Bad: The bolt still binds or misses—proceed to Bolt and lock mechanism or Hinges.

Bolt and lock mechanism

Goal: Check the bolt for binding or damage; lubricate or replace if needed.

  • Open the door. Turn the key or thumb turn and watch the bolt. It should extend and retract smoothly.
  • If the bolt sticks or binds, apply graphite lubricant to the bolt and keyway. Avoid oil—it attracts dust.
  • If the key will not turn, do not force it—call a locksmith. Forcing can break the key in the cylinder.
  • Good: The bolt extends fully and the lock engages—done.
  • Bad: The bolt still does not extend or the key will not turn—call a locksmith.

Hinges

Goal: Fix loose hinges or door sag so the bolt aligns with the strike plate.

  • Open the door and lift up on the handle. If the door moves up and down, the hinges are loose.
  • Tighten all hinge screws with a screwdriver. Use the longest screws that fit without protruding.
  • If the door sags and the bolt does not align with the strike plate, shim the hinge: remove the hinge from the jamb, add a thin cardboard or wood shim behind the hinge leaf, reinstall.
  • Good: The door is stable and the bolt aligns—test the lock again.
  • Bad: Still will not lock—call a carpenter or locksmith.

When to get help

Call a locksmith if:

  • The key will not turn or the key is stuck in the cylinder.
  • The lock mechanism is damaged or the bolt does not extend after lubrication.

Call a carpenter or handyman if:

  • The door frame is warped.
  • The door is heavy commercial-grade or fire-rated.
  • You have adjusted the strike plate and hinges and it still will not lock.

Do not force a key—it can break in the cylinder. For related fixes, see Fix a door that sticks or Fix a door that will not latch.

Verification

  • The door closes fully and the bolt extends into the strike plate when you turn the key.
  • The key turns smoothly in both directions (lock and release).
  • The door stays locked when closed and the bolt is engaged.
  • No binding or resistance when operating the lock.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Note whether the bolt extends into the strike plate when you turn the key.
  2. Strike plate alignment Adjust the strike plate so the bolt enters the hole.
  3. Bolt and lock mechanism Check for binding or damage; lubricate with graphite.
  4. Hinges — tighten and shim Tighten loose hinge screws; shim hinges if the door is misaligned.
  5. Call a pro Key will not turn, lock damaged, or repeated failures—call a locksmith or carpenter.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Whether the bolt hits the strike plate or does not extend
  • Strike plate alignment (bolt position vs hole)
  • Whether the bolt extends and retracts smoothly
  • Whether the key turns
  • Whether hinges are loose or the door sags
  • Steps already tried

Does the door close but the lock will not engage?

Close the door firmly. Try to lock it with the key or thumb turn. If the bolt does not extend, the key will not turn, or the bolt hits the frame, the lock is not engaging.

Close the door and try to lock it. Yes: Bolt does not extend, key will not turn, or bolt binds—proceed to check strike plate. No: If the door locks normally, you are done. If the door will not latch, that is a different problem.

Yes No

You can change your answer later.

Is the strike plate misaligned with the bolt?

The bolt should enter the strike plate hole when you turn the key. If the hole is too high, low, or recessed, the bolt will bind or miss.

Look at the strike plate hole and bolt position. Mark with a pencil. Misaligned: Adjust the strike plate or enlarge the hole. Aligned: Proceed to check bolt and lock mechanism.

Yes No

You can change your answer later.

Adjust strike plate and test

Loosen the strike plate screws. Move the strike plate so the bolt enters the hole. Enlarge the hole with a file or chisel if needed. Tighten screws. Close the door and turn the key. Good: Bolt engages—done. Bad: Still will not lock—proceed to bolt or hinges.

Done

Does the bolt extend and retract smoothly?

Operate the key or thumb turn. The bolt should extend fully when turned.

Open the door. Turn the key and watch the bolt. Sticks or does not extend: Lubricate with graphite; if still faulty, call a locksmith. Key will not turn: Do not force—call a locksmith. Extends smoothly: Proceed to check hinges.

Yes No

You can change your answer later.

Are the hinges loose or does the door sag?

Lift the door by the handle. If it moves up and down, hinges are loose.

Lift the door. Check hinges. Loose or sag: Tighten screws; shim hinges if needed. Good: Door stable—recheck strike plate or call a pro. Bad: Still will not lock—call a carpenter or locksmith.

Yes No

You can change your answer later.

Tighten hinges and shim if needed

Tighten all hinge screws. If the door sags, add a thin shim behind the hinge leaf. Close the door and turn the key. Good: Bolt engages—done. Bad: Still will not lock—call a carpenter or locksmith.

Done

No action needed or different problem

If the door locks normally, you are done. If the door will not latch (latch does not engage), that is a different problem—see the relevant guide.

Done

Call a locksmith or carpenter

Call a locksmith if the key will not turn, the key is stuck, or the lock mechanism is damaged. Call a carpenter or handyman if the frame is warped, the door is heavy commercial-grade, or you have adjusted the strike plate and hinges and it still will not lock. Do not force a key—it can break in the cylinder.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a door close but not lock?
Common causes: strike plate misalignment (bolt hole does not line up with the bolt), bolt binding against the frame, bent or worn lock mechanism, key cylinder that will not turn, or hinge sag that misaligns the door. Check strike plate and hinges first, then the lock mechanism.
Can I fix a door that will not lock myself?
Yes. Most lock failures are fixed by adjusting the strike plate, tightening hinges, or filing the bolt hole. If the key will not turn or the lock mechanism is damaged, a locksmith may be needed. Do not force a key—it can break in the cylinder.
When should I call a locksmith for a door that will not lock?
Call a locksmith if the key will not turn, the key is stuck, the lock mechanism is damaged, or you have adjusted the strike plate and hinges and it still will not lock. Security hardware often needs a pro for replacement or rekeying.

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