if you forget your device password or device working slowly. phone is not working properly you need to hard reset your smartphone. after reset your phone will be fresh. at first backup your all personal data contact, message, Photos, Videos and others
For Hard Reset Device battery 70% Up
1. At First Turn off Your Smartphone Nokia lumia 720
2. Now Press and hold Power key until the device Vibrate.
3. than Press and hold Volume down button until exclamation ( ! ) point on your screen.
4. Now you can release all keys
5. at this time press following sequence the keys Volume Up - > Volume Down -> Power - > Volume Down.
lumia 720 hard reset Step By Step