I had the same problem recently after I upgraded one of the packages. I tried “everything” and the only option that worked was the /Setup switch (I was logged in as Administrator, but don’t think that’s required).
c:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE>devenv.exe /Setup
c:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE>devenv.exe
https://msdn.microsoft.com/en-us/library/ex6a2fad.aspx