Which treatment works the best and fastest for broken bone?

Nothing. Bone will heal at its own rate. Treatment involves aligning the broken ends so they heal straight. It can be done externally with a cast or fixator, or internally with surgical placement of pins, plates and rods. Which is done depends on many factors.
See Orthopedist. Most broken bones need immobilization, which often means a cast. See the specialist.

Related Questions

I have a broken bone spur on my femur. What is the best treatment for this?

See below. Usually relative rest is all you need to employ to get adequate healing. Rarely, they need to be removed surgically if there is chronic pain.