I just twisted my knee and now i am unable to bear weight on the left leg. during this time i also experienced electric shock and burning below the knee into the lower part of the leg. what could have happened? hard to bend or straighten feels locked?

A severe twisting can result in a torn cartilage or serious tendon injury. If there's no associated swelling, I would hope that serious internal derangement didn't occur. For now apply cold compresses 20 minutes every few hours while you elevate the leg and,if you can take them, take anti-inflammatory meds like ibuprofen or naproxen. If not gradually improved consult an orthopedic surgeon

Since you have experienced a significant loss of knee function, it is important to seek an evaluation. Your regular doctor may be successful in managing this, but I suspect you will need to see an orthopedic surgeon. Am suspicious for a ligamentous or cartilaginous injury.