Please note, that to change a Keyboard Layout using the following method, you need to have more than one keyboard layout added to your language settings. See How to add a Keyboard Layout if you need help with that.
Step 1: Press and hold the Windows key
Step 2: Press spacebar.
NOTE: Pressing spacebar multiple times will toggle through the list of keyboard layouts you have; the layout you currently have selected will always be highlighted. See the image above for an example