Samsung X120 Hard Reset
Reset Via Master key
Start by turning your device on, to do it press Power button.
Then dialling screen of your device type this code in dialer: *2767*3855#
Next on confirm whole Factory reset process by tapping Call key again.
Now your phone should reboot.
Warning All your data including contacts, messages etc.. will be deleted! Make a copy of everything on your computer first! Take out the memory card and SIM card before full reset!