How To HTC Inspire 4G hard reset

Resetting the HTC Inspire 4G

Performing a factory reset using phone buttons

If you can’t turn on your phone or access the phone settings, you can still perform a factory reset by using the buttons on the phone.
With the phone turned off, press and hold the VOLUME DOWN button, and then briefly press the POWER button.
Wait for the screen with the three Android images to appear, and then release the VOLUME DOWN button.
Press VOLUME DOWN to select FACTORY RESET, and then press the POWER button. All data will be lost!

If you haven't update your phone yet pls do it. There is an HTC Inspire 4G for AT&T ROM Update  released on 7.31.2012
This update will only be available for AT&T HTC Inspire 4G Customers and will be sent to the device over the air - OTA firmware update for HTC Inspire 4G.
or
Press the MENU key.

Tap Settings.

Flick the screen UP.

Tap SD & phone storage.

Tap Factory data reset.

Tap Reset phone.

Tap Erase everything.

Your phone will reset all data.