No, the footer will not reappear when I uncheck the "right/left page are different function." Thanks for the suggestion, though. Yes, I have added text on the right page earlier in the section, before the footer dissappeared.
I should have made it more plain that it is not just the footer content that has dissappeared. The footer space itself will not show up when I move the curser over where it should be. There is no way to add any text because there is nothing to click on to activate the footer function. It is as if the "footer" is not activated in the inspector, yet it is.
For further clarification, I have not copied and pasted any text from other applications, such as Word,text editor, etc. Whatever is happening is going on within pages, without contamination from other software.
Your description confirms a behaviour some have seen when having may pages in a document with facing pages and show left and right page differently. Or it could be a corrupted document which often is rectified by copying the content of the document and paste it into a new blanc one.