I've updated my PC last night (January 29th) with only 3 updates available, libnl-3-200, libnl-genl-3-200 and libnl-route-3-200, all version 3.2.21-1ubuntu1, and after reboot my network manager was gone.
Reinstalling network manager nor restarting the demon manually did not helped.
I managed to download previous Trusty versions of those packages (3.2.21-1) and downgrade them back with dpkg. After reboot things went back to normal.
Cheers.