Just moved into a new house and the upvc porch door has a lock fitted with a handle attached. The key to the lock is lost and I would like to replace it. I can open and close the door using the handle, but the previous owner had lost the key to the lock. I have seen the barrel on sale in the local diy store and thought I'd get the old lock out to make sure of the size before I bought the new barrel. My problem is I can't get the old lock out. I was told that the key is needed to remove the barrel in order to replace the lock. I obviously cannot do this as I don't have a key. How can I get the barrel out in order to replace it? Any advice would be much appreciated.