Hi there! My name is***** am a computer professional with over 15 years of experience with both Mac and Windows computers, phones, tablets, and printers. It would be my pleasure to assist you with this. May I ask, is it the 4 digit passcode that has been changed or is it the password ***** your BarnesandNoble.com account that has been changed. If it is the 4 didigt passcode, can you also tell me what model your Nook is, please?