Background could not be detected

Good morning,

I am new to the Adobe programs and have great difficulties finding this one out. I have a pdf file that has been created with a black background and white writing, there are also images. When I go select change the background colour it tells me this"Adobe Acrobat cannot find a background in this file. If you see a background, it was not added in Adobe Acrobat or by an Adobe PDFMaker, and cannot be detected as such." How could I possibly still change the background to white and have the writing in black, I need this for printing purposes? Thank you.