Formatting N-Series Nokia Mobile Phone

--- Switch off the phone and Press and Hold 3, * and Call (Send or Green button) buttons. 
--- Then power on phone and keep holding on the 3 buttons till you come to a 'Format Screen' or 'Language Selection Screen'. 
--- This is the hard reset which helps the phone to tackle almost all problems and make all the 'settings' to default. After format, the security code would be reset to default 12345