When I rode horses there was the odd day I would be pitched off. An element of riding is that a horseman or horsewoman always gets back on, no matter how afraid you might be. Even if it's only for a few minutes, then you can get off and go do something else for awhile. It's important to get back on to quell any fears before they take hold after the shock of hitting the ground in an unflattering position.
When the rider returns to riding the horse they had the spill on, it is important to be firm but fair, while working on the area that caused the pitching. If the horse was being willfully disobedient, then perhaps the trainer asked too much of the horse. It is then necessary to go back to the beginning and work through the steps again to offset any future mishaps.