I have a Kryptonite U-lock and my key doesn't seem to be working, I'm not sure if the key is broken or the U-lock. How do I unlock my bike? Kryptonite isn't open and both the key and lock worked an hour before. (I have a theory that moisture inside the lock froze.)
This happened to me with a Kryptonite Evolution lock. I locked it, went for lunch, but afterwards the key just wouldn't unlock. After hours of oil, poking bits of wire, screwdriver waggles, help from strangers, I gave up. I tried again the next day, and gave up again.
In the end, I had to cut the lock with an angle grinder. Took 20 seconds tops. I took it back to the bike shop and they replaced it immediately. They said they replace about one a year on warranty.
They also recommended putting a bit of oil in the lock each month to keep it working smoothly.
I used deicer and WD-40. I think the WD-40 is what freed it enough for me to force it open. Then I wiped off a rust colored gooey film that it seemed to be getting stuck on.
Things I have tried with success on dodgy locks.
I found the angle of the lock makes more of a difference. Heaviest part towards the floor seemed more successful, though another lock like to be horizontal. There are some balls/bolts that pull in on lock. The angle can help assist
Pushing key in a varying depths and wiggling to free the lock.
Load of wd-40.
Pushing and pulling the Lock part while trying the key. Ensure the bolts are binding better.
Cool it (i.e waited till night)