I had this same problem and fixed it by adding the ‘npm’ directory to my PATH:
Right-click ‘My Computer’ and go to ‘Properties > Advanced System Settings > Environment Variables’.
Double click on PATH under the ‘User variables for Username’ section, and add
C:\Users\username\AppData\Roaming\npm obviously replacing ‘username’ with yours. Based on the comments below, you may need to add it to the top/front of your path.
Restart your console window or IDE and you should get a response from the bower command.