What do I need to do?

I have my 475 page book currently in PDF (a Proof) that was created in InDesign by another person. I tried to convert the PDF to Word using Export PDF, but it only produced most of the document in CAPS and nonsensical words, so probably incrypted by InDesign. I want to edit the book myself so what do I need to do to convert this PDF file to InDesign? I do not know what version of InDesign the other person used. I really don't want to have to re-type the whole thing over using Word...help! Thanks, Barbara