Can't connect to a specific WiFi network (Ubuntu 14.04)

From what I found on ubuntuforums.org you should

sudo apt-get purge bcmwl-kernel-source

reboot and you may need to blacklist b43 and/or ssb but you can try this after a reboot one line at a time and see if you are able to connect

sudo modprobe -r b43
sudo modprobe -r ssb

If you are able to connect only with using the modprobe -r b43 then echo "blacklist b43" | sudo tee /etc/modprobe.d/b43.conf

If it also took the modprobe -r ssb to connect then do both echo "blacklist b43" | sudo tee /etc/modprobe.d/b43.conf and echo "blacklist ssb" | sudo tee -a /etc/modprobe.d/b43.conf and wifi should connect