The buttons may wear or become loosely connected to the device. Going into the device and either replacing them or securing them should solve the problem. For more information, see the Nook Color troubleshooting page.

The device may just need to be restarted. The screen may be misaligned, requiring you to go into the device and straightening out. The screen may also have dirt or smudges causing misread input. The microSD card might be causing the display to accept wrong input, so restarting the device without the microSD inserted may help. There are applications for recalibrating the screen if the input is being read incorrectly. An undercharged battery might also be the cause. Recharging it may fix the issue. [Please refer to the Nook Color troubleshooting page for more information.

Try to charge your device. If it won't charge at all, the charger may be faulty. If a different charger won't charge the device, the problem is likely the battery. Otherwise, attempt to turn it on once it reaches full charge. Have a look at the Nook Color troubleshooting page.