If you need to shut off the water in your home, you need to understand how to operate the valve correctly. If you are working with a ball valve that has a straight handle, you need to put the handle in the position perpendicular to the pipe to turn off the water. When the handle is perpendicular to the direction of the pipe the water is on.
If you are working with a gate valve that has a circle-shaped handle, you will need to turn the handle clockwise until the water shuts off. You will likely need to turn the handle several times. To turn the water back on, turn the valve counter-clockwise until water flow resumes.