I had a PDF document which had to be converted to a word document( as I had to edit some content). As we don't have a PDF converter, I decided to import the document into Robohelp and generate a word document. But all the pdf pages were converted to images when I imported into Robohelp and generated the printed document all the content were displayed as images.(I was unable to edit the text in Robohelp as well).
Google "free pdf to Word converter" and you will get plenty of responses. Be aware some are free apps and some are free to download and trial. The latter may be OK in this instance.
Also be aware they all suffer from one issue. They will look correctly formatted but the styling is inline. Thus Heading 1 will look like a heading but it is not a heading style as Word understands it. If you select all the content and then press CTRL + Spacebar, all the text will be normal. I don't think there is any converter that applies styles as such.
Given that you are only using RoboHelp as a converter, you might like to also check a Word forum. Windows Secrets is a very good one.
I believe Open Office can convert from PDF to Word but I think you will find it has the issue above. If you do try that app, do so on a separate machine so that it does not affect your RoboHelp / Word link. It can do so in certain cases depending on how you set up Open Office. See Snippets on my site for that.