Use this Code ......
try
{
Microsoft.Office.Interop.Word.ApplicationClass wordObject = new Microsoft.Office.Interop.Word.ApplicationClass();
object File = @"C:\Documents and Settings\admin\My Documents\Visual Studio 2008\Projects\JyoBussinessApplication\JyoBussinessApplication\VinayakaEnterprise_letterhead.docx";
object nullobject = System.Reflection.Missing.Value;
Microsoft.Office.Interop.Word.Application wordobject = new Microsoft.Office.Interop.Word.Application();
wordobject.DisplayAlerts = Microsoft.Office.Interop.Word.WdAlertLevel.wdAlertsNone;
Microsoft.Office.Interop.Word._Document docs = wordObject.Documents.Open(ref File, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject, ref nullobject);
}
catch
{
}