Does the key spin continuously in the cylinder? Or does it not fully rotate to the unlocked position? Is it a deadbolt mortise or latch mortise. If the key is spinning continuously the tail piece on the cylinder is broke or has separated from the lock. Replace the cylinder but it will need to be rekeyed or replace the tailpiece if it came off and it is the type that screws on then you don't have to replace the cylinder or have it rekeyed. If there is internal failure in the mortise lockset, especially if it is 10 to 15 years old it should be replaced. This will normally require the services of a locksmith. If your're in Maryland let me know.
A key, or a Combonation
You can open a key lock on a door knob, or you can open a deadbolt lock on the door itself.
Some locks can be picked open when you don't have the key. You can use a wire hanger or a hair pin to pick a lock. If you cannot get the lock open, contact a locksmith for help.
Because your key is SEN
You cannot open a cylinder lock with a key inserted from the inside. The key only works from the outside to unlock the door.
Replace it. There about 24.00, you don't need a key to replace it. and if you drill it you have to replace it,so save your time. If your trying to rob a house you can get a pick set at a lock smith.
Not just with a key. There is a Special key that has a bus button on it. They push it......TADAAAA!It opens!with a key step1.take keys out of ignition step2. open backdoor emergency exit step3 lock emergency exit from the outside. Or just use the emergency button next to the door!! = they all have one.
donkey monkey John Key
No, there is no universal key that can open all locks. Each lock is designed with a specific key or combination that is unique to that lock. Attempting to use a single key to open multiple locks is not possible, as they are designed to be secure and prevent unauthorized access.
Lock
pick the lock or use a skeleton key
Just like any other key ... except that a master key will open more than one lock.