The key operates the lock. It just won't come out. If I can't get it out of the lock I should be able to remove them both and fit a new cylinder.
Back to the first part of my question, is 32mm from top to bottom the standard size?
If it doesn't free up, and you need to replace it, there is usually a screw in the edge of the door, that holds the lock in place.
Taking the screw out allows you to slide the "eurolock" out. These eurolocks are a standard height, but vary in length. Ideally take it to an architectural ironmongers, or maybe a builders merchants. If you don't want to leave the door open, measure its length. Maybe even draw a diagram with measurements.
Sandy
I have just measured both my front UPVC door and my patio doors.Both doors fitted by different companies.BOTH locks are 32mm top to bottom so I would say yess a standard size for domestic use doors
I was going to try the oil first but after looking I see there's nothing in the house but olive oil. I'll go to the shop later and get a tin of oil and if that doesn't work go tomorrow and get a new cylinder. It's good to know that the face of the cylinders is a standard size.
Just be aware that the locks aren't always symmetrical front to back, Sandy. I have two locks which are exactly the same length (ie, will fit the same thickness door) but the black central bit is a different distance from the keyhole (one is halfway, the other is offset).
Patio door locks are favourite for this problem due to the key being left in the cylinder. The key gets warm and one end and freezing at the other (ideal situation for creating condensation and corrosion) . Your pins have seized in the cylinder through lack of inactivity. It would be wise to replace the cylinder. They are so cheap it would be false economy not to.
If you can't remove the key after having tried the oil etc ... remove the screw that holds the cylinder from the side of the door frame.
At this point no one has mentioned that you will need to partially rotate the key (to about 10 past or ten to) so as to release the cylinder from the lock case. With the cylinder removed from the door only then can you identify the size of the cylinder,
The cylinder can easily be measured, from either end to the centre of the
lever. As a rule they are something like 45-50 or 40-45. If you order it from Amazon you will need this measurement, but if you go to the hardware store just take the cylinder with you for reference.
When you fit the new cylinder remember to remove the key once in a while, you know what will happen if you don't !