Your NOOK comes with a one-year warranty, for itself as well as for its charger and USB cable. The warranty isn’t transferrable, so if you give or sell your NOOK to someone, or get it or buy it from someone, the warranty doesn’t follow along.
However, if you got the NOOK as a gift, you, as the gift recipient, get the warranty. It says so right on the gift receipt.
The usual caveats apply to the warranty: If you’ve misused the device, damaged it by accident, tampered with it, and so on, the warranty is no good any longer.
If the NOOK goes on the blink during the warranty period, and you need Barnes & Noble to take care of it, call 1-800-THE-BOOK (1-800-843-2665) to make your claim. Barnes & Noble will either repair it and send it back to you, or send you a refurbished or new device.