First, verify that you have the correct firmware:
If it isnt installed, get it:
sudo dpkg -s linux-firmware-nonfree | head -n5
Now remove the usually conflicting package:
sudo apt-get install linux-firmware-nonfree
And the same for ndiswrapper:
sudo apt-get purge bcmwl-kernel-source <--this is the step that many miss
Check your blacklists:
sudo apt-get purge ndiswrapper*
If b43 or ssb is blacklisted, remove the line(s). Proofread carefully, save and close gedit.
gksudo gedit /etc/modprobe.d/blacklist.conf
Check what modules are forced to be loaded:
If wl or ndiswrapper is listed, remove them. Proofread carefully, save and close gedit.
gksudo gedit /etc/modules
Reboot. How is your wireless working?