I received the lovely gift of a NookColor for Christmas & yay, happy day! Now I'm ready to move my ebook library onto the device. But, there's a problem. When I sideloaded my previously purchased, non-DRMed books onto my NookColor, some of them didn't show up with a cover.
Off I went to research what to do. I tried a bunch of tricks. I followed several threads on how to fix the epub files. What has finally worked for me turns out to be rather easy.
This is what works for me:
1. Open Calibre. I use this to manage my ebooks and to load any and all ebooks not purchased from B&N onto the NookColor. Using it with the NookColor is as easy as plugging in the USB cord.
2. Find the book that doesn't have a cover. (If you downloaded the ebook directly to your NookColor, then select "Device" at the top to view the ebooks on the NookColor. Then right click book & select "Add Books To Library". Then go back to the "Library"--icon at top)
3. Right Click on the ebook and select "Edit Metadata" then "Edit Individually"
4. Find a copy of the cover online (perhaps from the ebook store where you purchased it).
5. Drag and drop the cover from your browser or file manager into the "Book Cover" area in the "Edit Meta Information" window.
6. Fix any other metadata info while there then select "okay"
[edited to add: To ensure the rest of this works, I've found that you might need to add a step here. Right click on book, select convert book individually, select EPUB in top right corner as output format EVEN IF you're already working from an epub file. This will recreate the epub file correctly with the new cover]7. Right click on title, select "Send to Device" and "Send to Main Memory". (or "Send specific format" if necessary. Choose epub!)
8. The ebook will either replace the one already there or copy a second ebook. If that happens, go to "Device" and delete the older ebook (right click, remove).
When creating the new cover, Calibre creates the metadata with the new cover and viola! It works on the NookColor.
This may sound like a lot of steps, but if you're like me & can't stand not having covers, it's worth it. Once you get the hang of it, it's fast and easy. And it works every time, so no more frustration.