Wifi on ubuntu
Many users face problem of their wifi not working on ubuntu 11.04+, because of Missing Drivers.
Now you can follow these simple steps to get the wifi drivers and your wifi working without restarting the system.
1. sudo apt-get install bcmwl-kernel-source
2. sudo modprobe -r b43 ssb wl
3. sudo modprobe wl
If you get some modules missing on step 2, try installing the headers and sources.
sudo apt-get install linux-headers-$(uname -r)