The keyboard on my Acer Aspire does not work, about ten keys including the Fn keys do not work. I am now using a wireless Microsoft keyboard which works fine except it has no Fn key. I have bought a S-Video cable to connect to my TV for but I can not use Fn with F5 to get the TV screen on. What do I need to press on this Microsoft keyboard? Please help!
If you are using Windows 7 or 8, you can press Win + P to switch the second monitor output.
If these keys on your keyboard, unfortunately, don't work either, right-click on the Desktop, select "Adjust screen resolution", then press "Connect to projector" link near the bottom to do the same thing.
I believe most Fn keys are driver dependent. If the driver of the keyboard and the driver of the graphics adapter don't interact with each other, this will not have any useful effect. The Fn key on an external keyboard can generally not perform the calls of the laptop keyboard because the Fn keys are hardware specific; they are not regular keyboard keys and can't be remapped.
More information on the workings of Fn keys in this Wikipedia article.
Instead, my recommendation is to check the graphics adapter driver's settings for a hot key section. Most driver packages have one.
There you should be able to set a key combination manually. It's also possible a combination is already set by default.
Here is an example of such a section from my extremely mediocre onboard Intel card:
If you have Windows Vista, 7 or 8 you can press Win+P then choose which screen(s) to use.