$ python3 manage.py runserver Python was not found; run without arguments to install from the Microsoft Store, or disable this shortcut from Settings > Manage App Execution Aliases. code example

Example: python was not found; run without arguments to install from the microsoft store, or disable this shortcut from settings > manage app execution aliases.

You need to download python from https://python.org. When in the installation, 
be sure to check the option that adds Python to PATH.