by MBI » 26 Aug 2011 10:22
Is this a traditional tubular lock like an Ace or AceII?
If so, if the plug is partway turned so it's stuck halfway between the locked and unlocked position, you need to continue picking it to get it fully to the locked or unlocked position. If you can't get it by picking, the other way is to file off the outside nub off the tubular part of the key so it can be inserted into the keyway while in a partially rotated position, then you can use the key to finish rotating it one way or the other. Just be aware that doing this will mean that when using this key from now on, it can come out of the lock at any point during rotation. If this lock is in use, that can be a bit disconcerting to others who are using it.
If it's not that kind of tubular lock, then as Squelchtone said, a picture could help us help you.