What to do when a key snaps
Stop turning the key and do not push tools or glue into the keyway. If part of the key is still visible, leave it in place and call with a photo if possible. Further movement can make extraction more difficult.
Extraction before replacement
Specialist tools may allow the broken section to be removed without replacing the lock. Once extracted, the lock can be tested to understand whether the break was accidental or caused by stiffness or wear.
Checking the cause of the break
A worn key can fail on its own, but a stiff cylinder, door misalignment or mechanism fault may also be involved. Finding the cause helps prevent a replacement key from suffering the same problem.