Clicking in left jaw and locking up means?

Jaw Click. That sounds possibly like TMJ (temperomandibular joint) syndrome. It's an inflammation of the muscles/ tendons of the area of the jaw. Best treatment is conservative. Avoid eating ice or hard, chewy foods and take an NSAID (like aleve/motrin) with food if it hurts. If the problem persists, you might need to be prescribed a muscle relaxant or have to use a mouth guard (to limit teeth grinding).