Q: The battery on my 4S dies in few hours.  How do I shut it off completely to then restore from ICloud?

The battery on my I4S has suddenly started dieing in just a few hours.  Previously it held charge for entire day.  I have turned off all apps, bluetooth, wifi, and everything I can without changing the battery life.  I was told to "hard" reset the phone.  How do I completely shut the phone down and have it reload from ICloud?