If you have access to Microsoft Word 2013 or later, you can simply open .pdf files in it and save the content as standard Word document (.doc, .docx). Without latest MS Word, you will need to rely on some sort of converter and there is literally dozens of them.
Open PDF file Open DOC fileAn universal picture and document converter
A program for ePUB conversions
One of the many PDF converters
A PDF to Word converter
One of the many PDF converters available