title: The application "Navigator" can't be opened
body: <p>When I click on the navigator it says, <code>The application "Navigator" can't be opened</code> 
  How can I fix this? It was completely fine few days ago and now I am trying to open it again and it says this suddenly. 
  I tried updating it but still no result.<br>
  I am using Mac book <code>OS Sierra version 10.12.3</code>. </p>
  
  <p>I tried updating the anaconda and navigator still not working</p>
  
  <pre><code>conda update anaconda
  conda update anaconda-navigator
  </code></pre>
  
  <p>command line : <code>anaconda-navigator</code> gives </p>
  
  <pre><code>Traceback (most recent call last):
    File "//anaconda/bin/anaconda-navigator", line 4, in &lt;module&gt;
      import anaconda_navigator.app.main
    File "//anaconda/lib/python2.7/site-packages/anaconda_navigator/app/main.py", line 16, in &lt;module&gt;
      from qtpy.QtCore import QCoreApplication, QEvent, QObject, Qt
    File "//anaconda/lib/python2.7/site-packages/qtpy/__init__.py", line 129, in &lt;module&gt;
      raise PythonQtError('No Qt bindings could be found')
  qtpy.PythonQtError: No Qt bindings could be found
  </code></pre>