Key Won't Turn in the Lock and What Usually Causes It

A key won't turn in the lock because of a fault with the key itself, the cylinder or the internal locking mechanism. According to the Master Locksmiths Association, this is one of the most common lock and key problems that a vetted locksmith is called out to fix. The exact cause always depends on the type of door and lock you have.

A very common call-out

A door lock contains small moving parts that endure daily wear, weather changes and heavy handling. Over time, these components can dry out, shift or break completely. When this happens, the key will often go into the lock but refuse to turn, leaving you unable to secure your home or get inside.

If the door will not open at all and you are standing on the wrong side of it, you will need immediate help. In this situation, you should read the advice on what to do if you are locked out. If you are safe inside or the door is open, you have time to diagnose the problem.

The table below shows the most likely causes for a key that refuses to turn, based on the type of lock fitted to your door.

These are the causes the MLA lists for each type of lock. A locksmith will need to inspect the lock in person to confirm the exact fault.

Check the simple things first

Before you assume the lock is completely broken, you should rule out the most basic causes. Some call outs come down to a simple mistake or a key that was never cut properly in the first place. You can check these details without any tools.

Run through this short list to see if the problem has an obvious cause:

• You are definitely using the correct key for this specific door.
• The key is an original or a high quality copy, rather than a badly cut copy that has always been difficult to use.
• The inside snib, which is the small black button on a night latch, has not been accidentally pressed down to lock the mechanism.
• There is no visible dirt, grit or debris blocking the keyway.

If the key is correct and the lock still will not turn, the fault lies within the lock itself. The next step is to identify your lock type and understand what has failed inside it.

Faults on uPVC and composite doors

Most uPVC and composite doors are secured by a multipoint locking mechanism. This is the long metal strip of hooks and bolts built into the edge of the door, which is worked by lifting the handle. The mechanism is locked in place by a euro cylinder, which is the barrel where you insert the key.

If the main locking mechanism breaks, the key will usually not turn and the door handle will not pull down. The central part of this mechanism is called the gearbox. A locksmith can often replace just the gearbox rather than charging you for a whole new metal strip. You can find more detail in the guide covering repairs for upvc doors.

Sometimes the mechanism is fine but the euro cylinder itself is failing. When this happens, a failing euro cylinder may stop the key going fully into the lock so it cannot turn at all. If the cylinder needs replacing, you should ask the locksmith to fit one that meets snap-resistant standards. Look for a TS007 three star rating, or a Sold Secure SS312 Diamond rating, to protect your home against lock snapping.

Night latches on timber doors

A night latch, sometimes called a rim lock or a Yale lock, is mounted on the inner surface of a timber door. It connects to a rim cylinder that passes through the wood to the outside. Because these locks rely on a simple latch and a cylinder, they are highly sensitive to the shape of the key.

On a wooden door with a night latch, the causes for a key failing to turn include using the wrong key or a bad key copy. Another common cause is the inside snib being pushed down, which deadlocks the latch and prevents the key from turning from the outside.

If the key and the snib are fine, the issue is likely a failed cylinder or a lock that is incorrectly fitted or the wrong size. If you are locked out with a night latch, a professional locksmith may open another door, such as a back door, first. Drilling the front lock is always a last resort and should only be done if non-destructive entry fails.

Mortice locks on timber doors

A mortice deadlock or sashlock is fitted entirely inside the body of a timber door. These are traditional heavy locks that operate using metal levers rather than pins. A replacement mortice lock should meet the British Standard BS3621, which is shown by a Kitemark on the lock faceplate. Insurers often ask what locks are fitted, so check your own policy wording.

The causes of a mortice lock failure include a poorly cut key, a faulty lock, a warped door, a lock that needs lubricating, or damage from tampering. Timber doors expand and contract with the UK weather, which can misalign the lock with the frame so the bolt cannot throw. Inside the lock, a lever spring that has failed or loosened will stop the key from lifting the levers to the correct height.

Age is also a cause. A lock that is over 20 years old may need a service or replacement.

What not to do when your key is stuck

When a lock fails late at night or when you are in a rush, it is tempting to use force. This is the worst approach you can take, because forcing a lock can turn a small fault into a bigger and dearer one.

You must keep these points in mind to avoid making the situation worse:

• Do not force the key to turn with pliers or grips, because a snapped key is a bigger and dearer problem to fix.
• Do not squirt household oils or lubricants into the keyway. If the lock needs lubricating, a locksmith can deal with it.
• Do not attempt to take the door mechanism apart yourself, especially on fire doors or main exit routes.

The Master Locksmiths Association strongly advises that you never try to lock a mortice lock with the door closed if you have a problem with it. If the mechanism jams while the door is shut, you could easily lock yourself out, turning a simple repair into an emergency entry job. If your key feels stiff or rough, test it while the door is wide open. If you have already broken the key, see the advice on extracting a broken key.

When the key turns on one side only

Sometimes a key will operate perfectly from the inside of the house but refuse to turn from the outside. This can happen with a mortice lock.

If a mortice key works on one side of the door but not the other, you should visit a local approved locksmith to have replacement keys cut. If a new key still does not work from the outside, the lock itself may be worn, as a worn lock or key is one of the causes the MLA lists, and the locksmith can advise whether it needs replacing.

How to avoid common locksmith scams

Because there is no government licensing of locksmiths in the UK, anyone can buy a set of tools and trade as one. This makes it vital to vet the person you hire. The Master Locksmiths Association runs a voluntary approval scheme where companies are vetted, have criminal record checks, and employ locksmiths who have passed an exam.

Rogue traders often operate as national call centres that advertise as local locksmiths. They quote a very low price on the phone, but that price multiplies once they are standing on your doorstep. They may arrive in an unmarked vehicle with no identification, refuse to give a firm price before starting, and demand cash only with no written invoice.

A common tactic is drilling a lock that could have been picked or bypassed without damage, forcing you to buy a replacement lock from them at an inflated price. On uPVC doors, a rogue trader might insist on replacing the entire multipoint mechanism when only the central gearbox or the cylinder had failed. Always ask for a total price, including parts, VAT and any call-out fee, before work begins.

What a repair or replacement may cost

Locksmith jobs are usually priced as labour plus parts. Some tradespeople charge by the hour, while others offer a fixed price per job. Many locksmiths charge no separate call-out fee, but some do, and VAT may or may not be included in the advertised price. You must ask the locksmith to clarify these points on the phone.

Price is heavily driven by the time of day and your location. Evenings, nights, weekends and bank holidays cost more than a weekday afternoon. If you can leave the repair until normal working hours, you will save money.

The table below shows the typical starting prices for common lock repairs and replacements.

These are MLA 2026 'from' prices and include VAT. Local quotes will differ, and London and some surrounding areas are typically about 20 to 25 per cent higher.

Your rights and protection as a customer

When you hire a locksmith, you are protected by UK consumer law. Under the Consumer Rights Act 2015, a service must be carried out with reasonable care and skill. The work must be done at a reasonable price if no exact figure was agreed in advance, and within a reasonable time. If the work is poor, you have a right to have it put right or get your money back.

Under the Consumer Contracts Regulations 2013, there is normally a 14-day cancellation period for work arranged at your home or by phone. However, this cooling-off period does not apply where you have specifically asked for a visit for urgent repairs. If the tradesperson sells you extra non-urgent work during that visit, those extra items are not covered by the exception.

If you live in a rented home, you should check your tenancy agreement and get the landlord's agreement before changing any locks. A landlord who changes the locks to keep a tenant out without a court order commits illegal eviction, which is a criminal offence. For advice on tenancy disputes, you should contact Citizens Advice or Shelter.

Common questions

Will the locksmith have to drill my lock?

Drilling should always be a last resort. A skilled locksmith will use non-destructive entry methods, such as picking or bypassing the mechanism, to open the door without causing damage. You should ask the tradesperson on the phone how they plan to gain entry and whether drilling is likely.

Does a stiff key mean I need a new lock?

A stiff key does not automatically mean the lock is broken beyond repair. For older mortice locks, a professional service and a freshly cut key may resolve the issue. If the lock or mechanism is worn, a locksmith can advise whether it needs replacing.

Can I claim the cost of a new lock on my home insurance?

This depends entirely on your policy wording and the circumstances of the damage. Check with your insurer before authorising the work, as cover varies and insurers often ask what locks are fitted.

How long does it take a locksmith to fix a lock?

Most single lock changes and lockouts take well under an hour to complete. Replacing a standard euro cylinder takes about 20 minutes, while fitting a new mortice lock or removing a snapped key takes around 30 minutes.

Next steps before you call a locksmith

If your key will not turn and you are ready to arrange a repair, it pays to be prepared. Taking a few minutes to gather information will help you get an accurate quote and avoid rogue traders. Follow this short checklist before you make the call.

Work through these steps to find a reliable local tradesperson:

• Get a total price before work starts, making sure it includes parts, VAT and any out-of-hours charges.
• Ask the tradesperson how entry will be gained and what standard the new lock will meet if a replacement is needed.
• Check the business has a real local address, a history of consistent reviews, and verify any MLA approval claim on the official MLA website.
• Ask to see identification when they arrive and insist on a fully written invoice once the job is finished.

Dealing with a broken lock is stressful, but choosing a vetted professional ensures your home remains secure and your money is well spent. Take the time to compare local options, ask the right questions, and find a locksmith near you.