These following commands worked for me. I think problem is with the new matplotlib version 3.3.1. I downgraded to matplotlib 3.0.3.
I uninstalled the newer version, then reopen command prompt and installed matplotlib 3.0.3. It's worked for me. I am not sure if it will work for you, so I recommend to check out the discussion.
pip uninstall matplotlib
pip install matplotlib==3.0.3
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