Hard Reset HTC HD7

First method:

1. Power off your device. 
2. Next hold and press Volume Up + Volume Down + Power button. 
3. Then wait for instructions on your screen, and when you see this instructions, then release holded keys.
4. Now follow the instructions to finish reset your device.
5. Done!

Second method:

1. Turn on your cell phone. 
2. Now from the Start screen, tap right arrow.
3. Then goto Settings -> About phone -> Reset your phone -> Yes.
4. Next you will see that your phone will reset and reboots.
5. Good job!

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.