Seekers factory reset your phone to let their stress and stress that this method can not you apply to any other phone, even if the phone from Blackberry phones because this may cause off the phone completely.
It is known that it is necessary to take a backup copy before you reset the factory settings where it is certain that all data on the phone will be deleted during the reset process.
How to Hard Reset BlackBerry 8120 Pearl
Remove and insert the battery into your phone.Press Power button until your handset is on.
if phone is not response then following step:-
Security wipe From the Settings Menu
Go to the device options.
Tap on Security and Privacy
select general settings.
choose menu keys.
Tap on Wipe Handheld.
Select the include third-party application check box to delete all third-party apps.
Now select Continue.
Then put in the word blackberry and select OK.
Then process should now begin to erase the data.