can u help me how to convert a pdf to docx file extension using a php or javascript?

Disclaimer: I'm working for this company.

You may use PDF Focus .Net library for this. The component supports PDf to Doc conversion.
try free online-service for the converting or
Take full PDF Focus .Net version

Use this code for the converting (converting PDf to DOC in PHP):

1. Add the SautinSoft.PdfFocus.dll to the GAC, launch:

gacutil.exe /i SautinSoft.PdfFocus.dll

2. Add the Assembly to the Registry, launch:

Regasm.exe SautinSoft.PdfFocus.dll /tlb:SautinSoft.PdfFocus.tlb

    /* Convert PDF file to DOC in PHP */
 $f = new COM("SautinSoft.PdfFocus");    

Cheer! ;)