1.- Factory reset or Soft Reset Nokia Lumia 710
Go to Settings > About > Reset your Phone (insert your lock code)
2.- Total Reset or Hard Reset Nokia Lumia 710.

Turn off phone the Nokia Lumia 710Press and hold the “Volume down“, “Power” and “Camera” buttons.When the phone start vibrates release the “power button”.Hold the “Volume down” and “camera” buttons for more than 10 secs and then release them.Nokia 710 will reset and turn on.
Important: To proceed to reset, the battery must be full and themobile device connected to the charger. If during the course of reset,the mobile stop receiving electricity it can ruin the internal flashmemory of the mobile device and stop function