Warning! Do this at your own risk! All your phone data (contacts,photos,videos,music,messages,aplications,games,files,) will be lost! Please make backup first if you can!
1.Power off your phone
2.Press together volume up + power key until you'll see Oranhe logo on screen
3.Press once power key to enter in recovery menu
4.Select with volume down "wipe data/factory reset" and press voulme up to confirm
5.Select with volume down "yes -delete user data" and press volume up to confirm
6.Wait until format ends
7.Press volume up to confirm "reboot system now"
8.Wait until the phone restarts
Thats's all!