How do i install network drivers?

I got Atheros9485 802.11b/g/n Wifi Adapter and Ubuntu 12.04 but the driver isn't installed. I can't use 'Additional Drivers' since I'm not connected to a network nor have the driver.

So what can I do? I'm new so if someone can explain in detail I would be grateful.

Your question is quite similar to "How can I install and download drivers without internet?", but only regarding a different networking device.

However, I think this is not going to solve your problem, since your device should be supported out of the box by the ath9k driver included in Ubuntu. Did you use an updated 12.04.1 image? That may resolve some issues. Try that out if you can't go online with that machine to run updates.

If that fails too, try using a workaround as explained here: "Ubuntu 12.04 wifi is not working (Atheros AR9485) [closed]"