This key might be the F10 key, F12 key or labeled with a symbol of an airplane. If your computer has a wireless key or button on or near the keyboard and the wireless activity light is off or amber in color, then press the key or button to enable your wireless adapter. If issue persists, continue with the below steps: Go to Device manager > select the WIFI drivers under network adapter> Right click go to properties > Under properties go to Power Management Tab> Uncheck ' Allow the computer to turn off this device to save power'.

I understand that you WIFI option disappears or not showing, please check this information: I would be happy to help you with your HP Pavilion notebook.