My phone nokia lumia 720 windows display is not working,i think O S also correpted. Shridhar 8431520198

If this isn't due to your phone being dropped in water, try doing a soft rest. To do this........Hold the "down volume" and "power button" at the same time for ten secs, until it vibrates, then let go of those buttons. The phone will now reboot. This will not erase any of the content on your phone (i.e., games, contacts list, programs, etc.)

Hope this helps. :)