Sounds as if your problem was initially caused by a problem within the lock itself, by forcing the handle you have probably fractured one of the components inside, possibly the follower (this is the part the handle spindle passes through). I would suggest you first remove both handles. This is easily done by removing the fixing screws on the internal handle then pull both handles off, on some handles there may also be a small screw on the side of the handle slacken this also. Inside each handle you will find 2 spring units known as cassetes. There is no need to remove the cyinder (the part the key fits into) With the handles removed position the spindle through the lock and try operating it with the door open using a pair of pliers. If the spindle rotates completely round the lock has failed and will need replaceing. On the edge of the lock look for the manufacturer. You will then need to search the internet in order to contact them. Replacement is not difficult just need to removed the securing screws in the door edge but you must make sure that the replacement is identical to the one you are removing as hole positions for the fixings and handles differ.
Good luck
Locktester, November 2006
