You can install pip installer from windows command prompt
first download the get-pip.py from the internet from this site https://bootstrap.pypa.io/get-pip.py then run the file from command prompt
python get-pip.py
This will download and install the pip installer into your machine
to use it use the following command
pip install <package_name>
or if that doesn't work use;
python -m pip install <package_name>
or you can use this;
py -3 -m pip install <package_name>
To update pip use the following command;
python -m pip install -U pip