iOS 6.1 has removed sound volume controls

On updating to iOS 6.1 this evening I find that I've lost all volume controls, except in the 'Sounds' section of 'Settings'.  The hardware buttons don't work; and the slider doesn't appear in apps.  There is no sound from the speakers during playback.  This is after a couple of power cycles and a hard reset.  Is there a fix?  Thanks.