Yes my jaw locks a lot!!!
It is very scary when it happens and also very very painful. It depends on if your tmj is a muscular problem or a disk/joint problem. If it is muscualar you should be able to go to a physical therapist who is trained in tmj to open you right up. These you still have to be very careful. I went to a pt who was trained in tmj, but yet did not know how to treat it correctly, he actually caused more harm then good.
I also have a mouth splint that helps a little. I have been put on a very stricted diet mostly liquids and some soft foods. the reason is if I do to much chewing my jaw can lock again.
Bascially my whole life has changed because my jaw lokcks. I am not suppose to talk that much or overwork my jaw muscles.
At first they thought that my jaw was only muscular but now they are not sure. I got some x-rays done and I should get the results back soon.
In the meantime check your posture and make sure that your chin is not sticking out. Try to sleep on your back (this is very hard for me), but it will put less stress on your joints. also ice helps a lot to ease the pain.
You could also ask your doctor for some muscle relaxers. These help calm the surrounding muscles down.