Hi, thanks for using JustAnswer.com I am Cris.
Please try to reset your Nook back to factory settings. If this is a software issue the reset will clear it up. After the reset you will need to connect to WiFi and register the Nook back to your account. Once registered you will have access to your books again.
Press the “Home” (“n") button to display the Quick Navigation menu on the Nook tablet.
Tap the “Settings” option in the Quick Navigation menu to open the Settings menu.
Tap the “Device Info” option to display the Factory Reset screen.
Tap the “Erase & Deregister” option to perform the factory reset. A confirmation screen opens.
Confirm the action by tapping “Erase & Deregister Device.” All data is deleted from the tablet, and the device is restored to original factory settings.
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