So, use the correct key to enable function keys and then use the F5 key to refresh your desktop or a page. See: Keyboard Volume keys not working in Windows.

The Fn key is also known as the function key, and on Windows and most Mac keyboards, you'll find it located in the bottom-left corner of your keyboard.

Function keys that enable convenient features like instant browser refreshing or screenshotting pages are lost unless you hold down the “fn” key on your keyboard.

Enable Toshiba Hotkey Cards Press and hold the "Fn" Function key to display the hotkey cards at the top of the screen.

Select Enable auto-repeat to toggle the auto-repeat function, which repeats the key that is held down multiple times until you let go.

Once you enable hibernation on your computer, click the "Choose what the power buttons do" link on the Power Options dialog box to enable waking your computer from hibernation using its keyboard.