It’s probably one of the scariest thing that could happen while driving. Your brakes fail.
The first thing, as with any emergency, is to try and remain calm. A calm person has a better sense of thinking.
Next, turn on your four way emergency lights to let anyone around you know that you are having a problem. If you have a cell phone handy, call for emergency help right away for any assistance you may need.
Find the smoothest part of the road and the most open part of the road. If you see a hill, try to climb it. This will cut down your speed. In you’re on a flat surface, just do your best to coast along until the car slows.
If your emergency brake still functions, this will stop the car completely. However, only use the emergency brake when the car is at a slow enough speed that it won’t cause you any harm. Of course, if there is the instance were you feel you may crash or hurt someone else, you may have no going but to pull the emergency brake.
Another option would be to use the guard rail as a way to stop. If you are the only one driving in the vehicle, get into the right lane. Slowly gauge your speed and distance and gently hit the guardrail. The friction will help to slow the car down to a safer speed. Yes, the car will probably be damaged, but at least you’ll walk away alive.