If, when you press the power button, the display remains blank or black, and there is no fan or disc noise, there may be a hardware issue. The computer must be able to recognize the hard drive and optical disc drive before you attempt to do a recovery. For instance, if the notebook has been dropped or jarred, you may need to reseat the hard drive and the memory modules to make the computer operational.
If the fan and hard drive can be heard and the LEDs blink, but the computer cannot display the Windows desktop, you may have a corrupted Windows or BIOS installation. If the notebook was made and sold in 2008 or later, it may have a UEFI pre-BIOS environment, and you can run hardware diagnostic tools by turning on the power and immediately pressing the f2
HP Startup Menu Overview
for more information.