Warning: This will remove all your content and should be a last resort when your nook will not work properly. If you can de-register first before taking this step.

1. Power down your nookColor/Tablet. Wait 10-15 seconds before continuing
2.  Press and hold power button and your "n" home button almost simultaneously (Power first and then the "n").
3.  Hold these until your screen flashes the "Touch the future of reading" message, wait 2 seconds and release buttons.
4. You will then get a prompt asking if you want to reset your nook to factory settings. Press the home button to continue. It will ask you to confirm. Press the home key again.
5. Your nook will deregister, reset, and when it reboots, you will see the introductory tutorials like it came from the factory.