Voice Mail notifications missing!  There is an application called 'Visual Voicemail'.  It seemed to worm its way onto my phone, where I was asked if I wanted to try it.  From the time I said OK, my voicemail notifications stopped.  The only way I knew that I'd received a Vmail, was to dial in anyway, where I would find that I have saved Vmail, even though I had not listened to them.
After I'd found that this app added no value to my experience, I didn't continue with it, but the notifications didn't return.  The solution I have found was to find the app and its settings.  From there it was easy to see; turn it off!  I tested voice mail and my notifications returned immediately.  I went the extra step and held down my finger on the app, until the trashcan appeared at the top of my screen.......gone!