HI please can u try Below COde
Refer Microsoft.Office.Interop.Word.dll and Office.dll from Add Reference MEthond
using System.Runtime.InteropServices;
using Word = Microsoft.Office.Interop.Word;
public Word.Document document;
public static Word.ApplicationClass wd = null;
public static int wordWnd = 0;
private static string filename = null;
object fileName = filename;
object newTemplate = false;
object docType = 0;
object readOnly = true;
object isVisible = true;
object missing = System.Reflection.Missing.Value;
document = wd.Documents.Add(ref fileName, ref newTemplate, ref docType, ref isVisible);
wd.Visible = true;
wd.Activate();
Vijay