Can you open synaptic package manager (menu>system>synaptic package manager.)
Click on settings then repositories, click on the other software tab and make sure there is a tick in the box next to "Canonical Partners"
Then type in the search box "broadcom" , right click on b43-fwcutter and click on mark to install (if it asks to install other drivers as well, select okay)
Then click on apply
When done, exit Synaptic Package Manager, reboot and see if it is working.