I convert everything I give my students into a PDF. This allows them to open it pretty much on any computer in our building or at home. Occasionally, I will run into a situation where I need the original document but it's not readily available. In those moments, usually crisis moments, I need an easy way to convert a PDF back into a Word doc.
The last time this happened, I did a quick search on the web and found several sites that promise to do just this. I used one that worked fine but limited the number of conversions you could do in a period of time. I needed two. It said I could only do one. I went elsewhere.
Ended up using PDF to Word. It's straightforward and simple to use.Upload your PDF. They convert it and send it back to you via email. I've tried several PDF conversions and they have all been satisfactory.
If you have to do this a lot, I'd recommend getting Acrobat Pro or one of the other desktop PDF reader/converters. If you are like me and only need to do this a couple times a year, stick with one of the online versions.
[Image captured from PDF to Word: http://www.pdftoword.com/]