1. Power off phone 2. Press and hold Menu Button ( middle ) + power on for at least 10 seconds 3. Android System Recovery Mode Appear 4. There are 4 options reboot system now apply sdcard:update.zip wipe data/factory reset wipe cache partition 5. Move the options to " Wipe data / factory reset " using volume down ( - ) button and menu button to confirm, because the touchscreen doesn't work in reovery mode 6. After the process done, phone will reboot. I hope I helped you.