How to Factory Reset an HP Pavillion
The HP Pavillion series of notebook computers run the Windows 7 operating system by default. If your computer suffers from a serious crash, you may need to reinstall the operating system on the computer to get it to work properly again. Fortunately, this process can be accomplished by using the HP Recovery Manager software, which lets you recover the PC back to the way it was when you purchased it fresh from the factory.
Turn on your computer.
Press the "F11" key repeatedly as the computer turns on.
Click the "System Recovery" button.
Click "Next," then click "Next" again.
Click "Finish" to complete the factory reset procedure.