A key that goes into the lock but won't turn is one of the most stressful door problems you can have — particularly if you're standing on the doorstep trying to get in. It's also one of the most common locksmith call-outs we receive. The good news is that it usually has one of a small number of causes, several of which you can deal with yourself.
Is It the Right Key?
Worth confirming before anything else. If you have multiple keys on a keyring — particularly if some are similar in shape — it's easy to try the wrong one without realising, especially in low light or when you're in a hurry. Try each key in turn before assuming something is wrong with the lock.
The Most Common Causes
1. The Lock Needs Lubricating
This is the most frequent cause of a key that turns stiffly or refuses to turn at all. Over time, the internal components of a lock accumulate dust, grit, and the residue left by unsuitable lubricants. This creates enough friction to prevent the lock from operating smoothly.
Apply a dry PTFE spray or graphite lubricant directly into the keyhole, then insert the key and work it in and out several times while gently attempting to turn it. Don't force it. In many cases this resolves the problem immediately. Never use WD-40 as a lubricant — it's a water displacer that leaves a residue attracting more dirt over time and can make the problem worse.
2. The Key Is Worn
Keys wear gradually with use, and a worn key may no longer align precisely enough with the pins inside the cylinder to turn it. This is particularly common with keys that have been cut from other copies rather than from the original. A worn key will often feel like it goes in correctly but stops just short of turning fully.
If you have a spare key, try that. If the spare works and the regular key doesn't, you need a new key cut — ideally from the original or from a locksmith who can cut it to code.
3. The Cylinder Is Worn or Damaged
Cylinders wear internally over years of use. The pins and springs that align when you insert the correct key can become stiff, corroded, or out of tolerance. If lubrication doesn't resolve the problem and the key is not worn, the cylinder itself may need replacing. This is a straightforward job — a new cylinder takes around 30 to 45 minutes to fit and immediately resolves the problem.
4. The Door Has Dropped or Warped
On a uPVC door with a multi-point locking system, the key only deadlocks the door after you've lifted the handle to engage the locking points. If the door has dropped or warped, the locking points don't seat correctly in their keeps, which puts pressure on the mechanism and can prevent the key from turning even with the handle fully lifted.
Try lifting the door slightly from the handle while turning the key. If this helps, the door has dropped and needs a hinge adjustment — not a lock replacement.
5. Something Is Wrong With the Lock Mechanism
On a mortice lock, a broken or displaced lever inside the lock body can prevent the key from completing its travel. On a euro cylinder, a failed anti-pick pin or worn cam can have the same effect. In these cases, lubrication won't help and the lock will need to be inspected and likely replaced.
Don't force it: The most important thing when a key won't turn is not to apply excessive force. Forcing a key in a seized lock risks snapping the key inside it, which turns a manageable problem into a more complicated and expensive one. If gentle pressure and lubrication don't resolve it within a few minutes, stop and call a locksmith.
When to Call a Locksmith
Call a locksmith if lubrication hasn't helped after a couple of minutes of gentle trying, if you suspect the key or cylinder is worn, or if the key has already snapped. A locksmith can diagnose the problem on arrival — in most cases it's immediately obvious whether it's a lubrication issue, a worn key, or a failing cylinder — and carry out any necessary replacement in the same visit.
If your key won't turn in Stourbridge, Halesowen, Dudley, Kingswinford, or anywhere in the surrounding area, call or WhatsApp on 07961 169 681. We'll give you a clear price before anyone sets off — no call-out fee.