Hi there. My name is*****'m sorry that you're having this problem. It would be my pleasure to help you. Can you tell me please what brand and model of computer you have? The correct function key can vary from one manufacturer to another. If I know the brand and model number I should be able to tell you which key to use. I am using a Lenovo T430 laptop. The key combination for it is the FN key in the bottom left corner and the F5 key on the top row of keys, but yours may be different.