Problems that often occur to Nokia Lumia 720 is the total death often though batteries have been or are still filled ... if things are going to be tried in the following way:
1. Nokia Lumia 720 total dead pressed the power button and volume down buttons simultaneously until you feel a vibrator vibrates once ... then off and wait for the Nokia Lumia 720 back to normal life ...
2. If not vibrating vibrator batteries possibilities have been exhausted, try to connect the charger while performing the first step ...
Based on experience in mobile data is not lost ... if the method fails Mobile should be brought to the nearest Nokia Care ...