Pdf File

First both Words and PDFs are editable, the difference is that Word documents are of floating type while PDFs are fixed type.
Anyway you can try out with Adobe's Acrobat SDK, but to be honest I'm not exactly sure if it is free:
http://www.adobe.com/devnet/acrobat/overview.html

Also in case you get interested in a solution for a backward task, aka converting a Word document to PDF file in C#, then you can use this .NET library for Word file's processing.
It provides a simple programmatic way for you to create a new PDF file with C# code.

hi ya,

It is not a tough work so far, there are numerous freeware available online that you can choose to convert PDF file to editable Word file, though PDF file is protected by passward or read-only mode.But make sure you have been authorized to do this.If you want to convert PDF file to word programmatically, the following links might be of help

http://stackoverflow.com/questions/5729874/how-to-convert-pdf-to-word-in-c-sharp
and vice versa

http://www.e-iceblue.com/Tutorials/Spire.PDF/Spire.PDF-Program-Guide/Convert-Text-to-PDF-with-C-VB.NET.html

regards

If you are a programmer, you can implement your own solution using a third-party toolkit (similar to leadtools) that supports loading PDF files and OCR features.
The idea is you need to load the PDF files as raster images, pass them to an OCR engine and then save the recognized characters (OCR result) to any document format (such as Ms Word).
I think even if the PDF file is secured, you should be able to load it as raster image.

The following contains sample project:
http://support.leadtools.com/CS/forums/36579/ShowPost.aspx

Word is Editable.
PDF is Read-Only.

You can convert Word to PDF (I mean, generate read-only copy from editable one)
It may not possible to convert PDF to Word Document. [Generating editable copy from PDF..]

However there may be hacking tools that convert pdf to word.