on the command line (make sure to cd into your working directory), issue this command:
touch .bowerrc
This will also work for other files common to webdev like .htaccess and .gitignore
Note: If you haven’t installed git bash for windows, you may not have support for the touch command. In that case (as mentioned in one of the comments here), the easiest way to accomplish this is via the cli with:
echo "" > .bowerrc