How to Fix a Door Lock That Won't Unlock

A door lock that won't unlock is one of the most stressful home problems — especially if you're locked out or trapped inside. Here's a calm, step-by-step guide to getting it open and fixing the underlying cause.

Why Won't My Door Lock Unlock?

• Dry or corroded cylinder: Lock pins are seized and won't respond to the key
• Wrong or worn key: The key no longer matches the worn pins
• Bolt under pressure: The door has shifted and the bolt is pressing hard against the strike plate
• Frozen lock: Moisture inside the cylinder has frozen
• Broken key fragment inside: A piece of key is blocking the cylinder
• Broken internal mechanism: The cam or tailpiece inside has failed

Step 1: Don't Force the Key

Forcing a stuck key can snap it inside the cylinder, making the situation much worse. Apply gentle turning pressure only while trying the steps below.

Step 2: Lubricate the Cylinder

Spray lubricant into the keyhole, insert the key, and gently work it back and forth. This fixes the majority of stuck locks.

• DuPont Silicone Lubricant — best all-around lock lubricant, won't attract dirt
• WD-40 Multi-Use 3oz — penetrates rust and corrosion quickly
• DuPont White Lithium Grease — longer-lasting, ideal for cylinder internals

Step 3: Relieve Bolt Pressure

If the door has shifted and the bolt is pressing against the strike plate, the lock won't turn. Push or lift the door slightly while turning the key to relieve the pressure. If this works, fix the door alignment afterward.

Step 4: Thaw a Frozen Lock

For exterior locks in winter:

• Apply hand sanitizer (alcohol-based) to the key and insert it
• Use a commercial lock de-icer spray
• Warm the key with a lighter for a few seconds before inserting
• Never use hot water — it refreezes and worsens the problem

Step 5: Try a Spare Key

If your primary key is worn, a spare may work where the original won't. If the spare works but the original doesn't, get a new key cut from the spare.

Step 6: Remove a Broken Key Fragment

If a key has broken inside, spray lubricant first, then use needle-nose pliers, a broken key extractor, or a bobby pin to grip and pull the fragment out.

Step 7: Replace the Lock Cylinder

If none of the above works, the cylinder is worn beyond repair and needs replacement.

• Mortise/Rim Lock Single Cylinder Replacement — satin brass, includes 5 keys, standard indoor & outdoor use

Step 8: Call a Locksmith

If you're locked out and can't resolve it yourself, a licensed locksmith can open the door without damaging it and replace the cylinder on the spot. This is always preferable to forcing the door.

Prevention

• Lubricate all locks twice a year
• Replace worn keys before they break
• Fix door alignment issues promptly to prevent bolt pressure
• Keep a spare key with a trusted neighbor