Samsung Galaxy Gio S5660 Hard Reset
1. Turn off the device. If its stuck then try to pullout the battery for a minute and then put it back in.
2. Press down the volume key and the power key.
3. Then release the power button.
4. Now a menu appear give you the options to Fastboot, Recovery, Clear Storage and Simlock. Select Clear Storage. use the volume down button to navigate the menu.
5. Then press and release the power button.
6. Finally wait for your device to reboot.
once the Samsung Galaxy Gio Restarted it should now go back to the default factory setting.
Use this method to hard reset your Samsung Galaxy Gio S5560 phone: Enter *2767*3855#. Warning! All your data including contacts, messages etc. will be lost! Copy all your necessary data/contacts/messages etc. to sim or make backup on your pc before full reset.