unlock LG Optimus Net P690 using hard reset
If it does not restore to the original condition, use hard reset to initialise your phone.
When the phone is turned off, press and hold the Home key + Volume down key + Power key
for over ten seconds. When the screen shows the LG logo, release the Power key.
After the screen shows the hard reset screen, release the other keys.
Leave your phone for at least a minute while it performs the hard reset, then your phone will be turned on.
Caution: if you perform a hard reset, all user applications and user data are deleted. This cannot
be reversed. Remember to back up any important data before performing a hard reset.
or
To reset your LG Optimus Net P690B phone to factory settings and erase all the data on your phone, touch Menu > Settings> Privacy > Factory data reset > Reset phone.
Resetting the phone does not erase any system software updates you have downloaded or any files on your microSD card,
such as music or photos. If you reset the phone in this way, you are prompted to re-enter the same information that you did when you first started Android.
or
You can use LG Mobile Support tool to repair your LG cell phone, after download select menu Customer Support > Recovery Phone
