Refund would need to be through Customer Service. 'Fixing' it would be through CS or at a store, if it's possible.
We had one book that wouldn't show on the HD. I sideloaded it and it works fine.
You will need to check to see if the book that won't download is a PagePerfect PDF format. If that is the case then it probably won't ever download to the HD+ as that format is not supported on the HD+. You will be able to download and read it on a computer with the Nook App. Most likely you will not be able to get a refund for the book because you can download and read it on a computer.
I have had this happen a number of times myself (a bit of a slow learner) but now I check that a book is readable on the HD+ before I buy it.
Good luck with your book. Beth
I bought a book about a month ago that was a Page Perfect book. I was unaware it was different until I tried to download it to my PC and needed to install Nook Study to do that. I had no trouble downloading and reading it on my HD+ though. It is not supported on my NGL and I also can't open it in Calibre.
Here's the end of the story of my (repeated, identical, multiple) failures to download my PagePerfect book. (Summary: it failed to download in the B&N store, failed (identically) to download at home, on two different HD+'s, failed to download to Nook for PC, succeeded on Nook Color and on Nook Study). The good news is that I just sideloaded the file to the HD+ and I am able to read it with the PDF Reader (but not with ezPDF).