Ubuntu – Can’t enable the proprietary drivers for Broadcom BCM43142 wireless after installing Ubuntu 14.10? Offline package required

It seems that there is some problem occurred when you installed Wireless Broadcom 802.11 driver. You can give a try to followings:

1. Open a terminal and execute following commands:

   $ sudo (jockey-gtk &)
   $ sudo update-grub
   $ sudo update-initramfs -u
   

   jockey-gtk will automatically searches all available drivers and try to fix it. Then restart your system.

2. Try to reconfigure installed Broadcom Wireless Driver

   $ sudo dpkg-reconfigure bcmwl-kernel-source
   

   if it still doesn't work then re-install it by completely removing it:

   $ sudo apt-get autoremove bcmwl-kernel-source
   $ sudo apt-get --purge remove bcmwl-kernel-source
   $ sudo apt-get install bcmwl-kernel-source
   

3. Try to update your system, sometimes updating fixes a lot of issues. Update your system after removing any broken packages, residual unused packages, execute these commands:

   $ sudo apt-get autoremove
   $ sudo apt-get autoclean
   $ sudo apt-get install
   $ sudo apt-get update
   $ sudo apt-get upgrade
   

I hope any of these steps work for you. Reply if something goes wrong..

You need to install wireless driver.

Insert your Ubuntu installation disk or a flash drive and copy these files from the installation disk to your Home directory:

pool/main/d/dkms/dkms_XXXXX.deb
pool/restricted/b/bcmwl/bcmwl-kernel-source_XXXXX.deb

Then run the following in terminal:

sudo dpkg -i *.deb

If you have UEFI BIOS, you need to disable Secure Boot to load the driver.

18.04 update:

The solution won't work on 18.04, because build-essential and its dependencies are not installed by default. The dpkg command will complain that dependencies are not installed.

You can manually find the required packages on the installation media ("pool" directory sorted by alphabet) and install them the same way as the dkms package. I hope nothing is missing there.