It's supposed to be FN + F2, that would be a special [Function] key held down while tapping the [F2] key. But you probably knew that.
The manual (for the hardware?) is here:
http://support.gateway.com/s/Manuals/Mobile/8511184.pdf
The whole kit-and-kaboodle web page is here for that laptop, including support links and chat with Gateway.
Ummm if it won't turn on that way, perhaps the driver got messed up. And you should download it and re-install it.
If you are out of warranty, and technically and mechanically adept, you may want to try and re-seat the wireless module in the laptop. I didn't say it would be easy to get to. And as the Myth Busters say - you shouldn't try this at home. If you're not confortable with that level of work - it's best to take it to a shop.
Of course as a worse-case-scenario option - you could purchase an after market wireless card and use that.