####1 : First of all, get your system up-to-date.
$ sudo apt-get update
####2: Next, what we are going to do is that we are going remove the installed driver at first and then move on.
$ sudo apt-get purge bcmwl-kernel-source
####3: So as we have removed the driver now we are going to re-install the driver
$ sudo apt-get install linux-generic bcmwl-kernel-source
####4: Done. reboot your system now.
$ sudo reboot
Hope this will work for you guys. If not comment below.
Cheers.
Note: If you don’t know which wifi card you have, then do this in the terminal(Ctrl+Alt+T)
$ lspci
This will give your network controller name.