Hello,
You may have once tried to open your python files (*.py) with a text editor (WordPad) letting Windows assume all python file should be openned this way in the future.
You need to reverse this in your Windows Explorer, Tools's menu, Folder Options, look for the File Types tabs and delete file association betwen *.py and Wordpad. You need in fact to associate the extension with the python.exe program you should find under c:\Python27\
Note that it may be that need to re-install python, to let it associate *.py with python.exe
Hope this helps.
Sébastien.