Quick answer
Common causes are a worn or wrongly cut key, a dirty or worn cylinder, or a door out of alignment putting pressure on the bolt.
Quick checks
Try a spare key. Try with the door pushed firmly shut, or with the uPVC handle fully lifted. If it turns then, the problem is alignment, not the lock.
What not to do
Don't force the key, as it may snap inside the lock. Avoid oil-based lubricants, which attract dirt. A dry PTFE or graphite lubricant is better.
When to call a locksmith
If the key still won't turn, or it's turning but nothing happens, the cylinder or mechanism probably needs repairing or replacing.
Related services
- Lock Repair — Sticking, jammed or broken locks repaired properly.
- Euro Cylinder Replacement — Worn or vulnerable euro cylinders swapped for anti-snap models.
- Door Lock Repair — Front, back and internal door locks that won't lock or latch.