The following commands (one at a time should take care of you)
Originally Posted by somaidra
The first makes sure that the sta driver is in place, the second and third blacklist the two drivers brcmsmac and bcma which clash with the correct sta driver. Copy/paste or make sure your typing is correct!
sudo apt-get install --reinstall bcmwl-kernel-source broadcom-sta-common broadcom-sta-source
echo "blacklist brcmsmac" | sudo tee -a /etc/modprobe.d/blacklist.conf
echo "blacklist bcma" | sudo tee -a /etc/modprobe.d/blacklist.conf