What are good ways to unlock your jaw?

Not easy: If your jaw is "locked" then cartilage is in the way of closure. You have to manipulate your jaw to undo this. You can try gradually moving your lower jaw left and right and this sometimes will work. The other option is to open it a little more, slowly and hold it at each point to release the stuck point. These will usually work but you might need to see an ENT specialist to help.