The fastest way to quickly access what you are reading now is through the 'My Library' section. My Library displays content you have most recently read or purchased from any NOOK device or NOOK Reading App. Items are sorted by most recently added, not by publication date.
You can sort the items in Library by Title and for books also by Author. You can also choose to show all Library items at one time, or view just one type of content at a time, such as books, magazines, etc.
Another way to locate the item you're reading now is to bring up Reading Tools menu. Access the Reading Tools menu by swiping up from the bottom of the screen or swiping down from the top of the screen. Tap or click on the cover to return to the item you are currently reading.