This machine has only wifi connection, no wired to connect to Internet.
The worst thing is the native ath9k driver is failed, that means you won't have any resource to connect outside the world..... :(
Thus, here is what I have done for the solution (easy job) to get my wifi back to real life.
1. need a smart phone to share network with usb connection....:)
2. if not, then you may need to have any other same ubuntu 12.04.2 device to download all the packages, then copy to your system. (apt-get download package-name)
3. apt-get update (for updating your source list)
4. apt-get install linux-headers-generic build-essential
(for compiling driver later)
5. download the compat driver from the link below
https://www.kernel.org/pub/linux/kernel/projects/backports/stable/
from the link, you need to find out the package name "compat-drivers-3.9-rc4-2-s.tar.bz2" and download to local.
6. extract file and enter the folder
7. sudo su (easier to do all jobs later)
8. ./scripts/driver-select ath9k
9. make;make install
10. you can reboot and get your wifi back now.
