One of the most common problem one faces after a fresh install of Ubuntu is the loss of Wireless Network. And believe me that is the biggest pain for a normal user. The problem double-folds if the wireless adapter is broadcom (do not know what is your wireless adapter? click here). Some of the general problems are showing no wireless adapter, showing wireless adapter but detecting no wireless networks etc. The solution provided here assumes that you have access to wired network. If not then you can follow the same solution with a little help of this post. If yes, then follow the instructions given below:
1. Open the terminal (Ctrl+Alt+T) and type the following command to install the Synaptic Package Manager:
sudo apt-get install synaptic
2. Now open the Synaptic Package Manager and search bcm in it. Uninstall or remove any package if already (related to bcm) specially bcmwl-kernel-source
3. Now install these two packages: b43-fwcutter and firmware-b43-installer. The picture below should be helpful.
4. Disconnect the wired lan cable and restart the computer. The same steps could have easily been performed in terminal itself but I have preferred the graphical way to ease it for beginners.
You should get wireless after this. If the problem still persists then try either of these solutions:
Hope it helps you in getting wifi. Do subscribe to the blog to stay in touch. And do not hesitate to ask questions and provide feedbacks and suggestions. Moreover a simple word of thanks encourages a lot. Enjoy
Source: Ubuntu Forums