WIFI not working in Ubuntu, what to do??

If you have freshly installed Ubuntu and your WIFI is not working. Then you should follow the following steps to hopefully resolve the issue.

Goto System/Administration/Hardware drivers
See if any drivers are listed as to be installed or in-active.
In this case install the driver and enable it.
Restart the machine

Still not fixed
If you are using a Compaq machine in particular and also in general, sometimes the drivers are installed properly but the wireless button does not work. In that case, first check to see if it is disabled. If it is, then enable it

rfkill list all
# if blocked =yes then try next command
rfkill unblock all

If you still have problems then may be you have the BCM4312 802.11 b/g rev(01) card
Check to see if this is the case

lspci | grep 802

If in the output you see BCM4312 802.11 b/g rev(01)
then you should do the following

sudo su
apt-get update
apt-get install bcmwl-kernel-source
shutdown -r now

You would need to restart for the changes to be effective
If in case it still does not work, check in system/administration/hardware drivers. A LINUX STA driver will be listed. Click on install and then enable it in the same menu. After this reboot.
Everything should be working now! :)

Genius G540 Universal Programmer software installation

You can download the software from here
Run setup
Disconnect programmer from PC if connected
Run setup in the folder USB_Driver
Connect the programmer and let windows automatically install the driver, you may cancel searching for driver from windows update if it is taking too long.

If still in doubt read the file setupguide.rtf

Dell 1545 wireless and Ubuntu

As it turns out wireless network does not work on Dell 1545 in Ubuntu. Here is a simple solution

Ubuntu:
------
Go to System->Administration->Hardware Drivers
Choose the Broadcom STA wireless driver
Activate

Sometimes the driver does not show up in the Hardware Drivers choices. In
this case, try reinstalling the driver from the GUI or shell like this:

From the GUI:
Package Manager (System>Administration>Synaptic Package Manager). Click the
Reload button in the upper left corner of Synaptic to refresh your index then
search for and reinstall the package named bcmwl-kernel-source.

Code:

sudo apt-get update
sudo apt-get --reinstall install bcmwl-kernel-source 

in case the package was not already installed try
Code:

sudo apt-get install bcmwl-kernel-source

In either GUI or text case, after reinstalling, reboot your machine.

Or you may wish to download and manually install the driver from this link http://www.broadcom.com/support/802.11/linux_sta.php


Ndiswrapper method

If you don not have luck with the above method or you have a different device then you can try the Ndiswrapper technique. A detailed walk-through is given here https://help.ubuntu.com/community/WifiDocs/Driver/Ndiswrapper. For the curious, basically Ndiswrapper allows you to install and use windows drivers on Ubuntu. Good ain't it :D