Hello,
I believe we sent you an email today regarding this issue, but our recommendation would be to find out more about what file formats the Nook can open and to make sure that you are using such a file format for your e-book. PDFs are widely accessible and should be fine on any e-reader as far as I am aware.
Unfortunately, all we do is deliver your file in the same format that you uploaded it in. We can't help with supporting your product or helping your buyers use it.
