title: Cannot open anaconda suddenly
body: <p>Today I found I cannot open anaconda navigator, which operated just fine before. At the same time, spyder could not be open either, but <strong>jupyter notebook</strong> and <strong>anaconda prompt</strong> are available. I tried different methods following instructions online.</p>
  
  <pre><code>1) conda update anaconda-navigator and reboot the system
  2) anaconda-navigator --reset
  </code></pre>
  
  <p>, but it shows the error as follows:</p>
  
  <pre><code>Traceback (most recent call last):
    File "C:\Users\User\Anaconda3\lib\site-packages\qtpy\__init__.py", line 169, in &lt;module&gt;
      from PySide import __version__ as PYSIDE_VERSION  # analysis:ignore
  ImportError: No module named 'PySide'
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "C:\Users\User\Anaconda3\Scripts\anaconda-navigator-script.py", line 6, in &lt;module&gt;
      from anaconda_navigator.app.main import main
    File "C:\Users\User\Anaconda3\lib\site-packages\anaconda_navigator\app\main.py", line 22, in &lt;module&gt;
      from anaconda_navigator.utils.conda import is_conda_available
    File "C:\Users\User\Anaconda3\lib\site-packages\anaconda_navigator\utils\__init__.py", line 15, in &lt;module&gt;
      from qtpy.QtGui import QIcon
    File "C:\Users\User\Anaconda3\lib\site-packages\qtpy\__init__.py", line 175, in &lt;module&gt;
      raise PythonQtError('No Qt bindings could be found')
  qtpy.PythonQtError: No Qt bindings could be found
  
  (base) C:\Users\User\Anaconda3&gt;anaconda-navigator --reset
  Traceback (most recent call last):
    File "C:\Users\User\Anaconda3\lib\site-packages\qtpy\__init__.py", line 169, in &lt;module&gt;
      from PySide import __version__ as PYSIDE_VERSION  # analysis:ignore
  ImportError: No module named 'PySide'
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "C:\Users\User\Anaconda3\Scripts\anaconda-navigator-script.py", line 6, in &lt;module&gt;
      from anaconda_navigator.app.main import main
    File "C:\Users\User\Anaconda3\lib\site-packages\anaconda_navigator\app\main.py", line 22, in &lt;module&gt;
      from anaconda_navigator.utils.conda import is_conda_available
    File "C:\Users\User\Anaconda3\lib\site-packages\anaconda_navigator\utils\__init__.py", line 15, in &lt;module&gt;
      from qtpy.QtGui import QIcon
    File "C:\Users\User\Anaconda3\lib\site-packages\qtpy\__init__.py", line 175, in &lt;module&gt;
      raise PythonQtError('No Qt bindings could be found')
  qtpy.PythonQtError: No Qt bindings could be found
  </code></pre>
  
  <p>So I tried different methods to reinstall pyqt as follows:</p>
  
  <pre><code>1) conda install pyqt
  2) conda install --force qt 
  3) pip3 install PyQt5
  </code></pre>
  
  <p>But still not working. I really wonder how I could fix this. </p>
  
  <p>And now when I ran anaconda navigator in the prompt, I got </p>
  
  <pre><code>anaconda: error: argument : invalid choice: 'navigator' (choose from 'auth', 'label', 'channel', 'config', 'copy', 'download', 'groups', 'login', 'logout', 'notebook', 'package', 'remove', 'search', 'show', 'upload', 'whoami')
  </code></pre>
  
  <p>PS: my python version is 3.5, and anaconda has been updated to the latest version. </p>
  
  <p>PS2-Possible Solution: I ran conda install <code>PySide</code> on prompt and it downgraded some of the packages, where I remembered few days ago I upgraded beautifulsou4, please be very aware when upgrading packages on anaconda ! </p>