How To Hard Reset-Nokia Lumia 820

Nokia Lumia 820 hard reset

With the phone turned off.

Press and hold the power key until it vibrates.

after press and hold the down key volume till the exclamation mark will be shown on the screen, release the button and input this combination.
Volume Up > Volume Down > Power > Volume Down.

Warning!
By performing "Factory Reset", all user data will be ERASED. You MUST backup PRIOR to running factory reset & Web update.

If your phone isn't responding
Do the following:
• Switch the phone off, and remove the battery. After about a minute, put the battery back in, and switch the phone on.
• Update your phone software.
• Reset your phone. This restores the factory settings, and erases all your personal content, including apps you've purchased and downloaded. On the start screen, swipe left, and tap Settings > about > reset your phone.

To hard reset your Nokia Lumia 820

or

1. On the Start screen, tap .
2. Tap Settings > about phone.
3. Tap reset your phone, and then tap yes.