Resolve dell inspiron 5520 wireless detection problem in ubuntu

Most of the time when you trying ubuntu on your personal laptops, 

you may end up in wifi connectivity problem.

Here are the steps to resolve:

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go to terminal or use ctr+alt+t to open a terminal and execute the following commands, 

sudo apt-get install linux-headers-generic
sudo apt-get install --reinstall bcmwl-kernel-source
sudo modprobe wl 

Tested in Dell inspiron 15r 5520 - works great. 

thanks to :http://askubuntu.com/questions/227394/lost-wi-fi-after-ubuntu-12-10-precise-pangolin-upgrade