To perform a hard reset using the device key buttons follow these steps:
1. Turn off the device or remove the battery for a few seconds.
2. Insert back the battery.
3. Press and hold the Volume down button.
4. While continuing to hold Volume down button, press and hold the Power button for 5 seconds then release.
5. When you see the Android logo appear, you may then release Volume Down.
6. Use the Volume Up/Down buttons to highlight Factory reset.
7. Press the Power button to select.
The hard reset operation will start . It could take several minutes to finish , after that the MyTouch 4G will reboot.