Thanks, Macropod!

I did what you said as it was saving as Web Layout and not Print Layout. I've changed it and everything looks normal again. Easy when you know how!

Thank you so much. I've spent so much time puzzling over this and I'm so grateful for your help. I have a fairly good understanding of Word but this was the first time I had edited a document for an ebook and somehow I missed the Web Layout v Page Layout! Now I know for future use, so thank you very much.

Problem solved.