How to hard-reset samsung galaxy ace
To hard reset samsung galaxy ace,


Turn off your phone
Press and hold volume up, home, power button at the same time.
The Recovery appears, use volume up/down to navigate, power to select
Navigate to wipe data/factory reset and select
Navigate to Yes - delete all user data and select


And now resetting... (Make a backup of your phone first)

Navigate to reboot system now and select to get out of recovery.