Using pip on windows is a little different than a lot of the pip documentation. If you have Python 3.3 or higher, you can use the py python launcher for Windows:
py -m pip --version
If you have Python 3.2 or less, then try this:
python -m pip --version
If you get an error message that says: 'python' is not recognized as an internal or external command, operable program or batch file, then python is not on your system path. So you'll need to give the full path to the python executable:
c:/python27/python -m pip --version
In this example, c:/python27 is the folder where my python 2.7 version is installed.