If your PC runs normally, you really need to use a secondary screen. Please check your laptop’s manual for some information about the button combination you have to use. With some HP models the working combination is to hold the FN button and press F4. If nothing happens, hold the FN button, press F4 once and then press right arrow three times. Have in mind that your PC may use different button combination. Confirm that with the manual or the manufacturer’s web page.