public static string TransformXml(string inputXml, string xslVirtualFile)
{
    //- Load XSL Transformation -----------------------------------------------------------
    xslVirtualFile = HttpContext.Current.Server.MapPath(xslVirtualFile);
    XslCompiledTransform xslTransform = new XslCompiledTransform();
    xslTransform.Load(xslVirtualFile);
    StreamReader streamReader = new StreamReader(xslVirtualFile);
    string xsl = streamReader.ReadToEnd();
    streamReader.Close();
    xsl = xsl.Replace("{appRootUrl}", Helper.ApplicationRootUrl);
    MemoryStream ms = new MemoryStream(System.Text.ASCIIEncoding.ASCII.GetBytes(xsl));
    xslTransform.Load(new XmlTextReader(ms));

    //- Load XML Data ---------------------------------------------------------------------
    StringReader sr = new StringReader(inputXml);
    XmlReader xr = new XmlTextReader(sr);
    StringWriter sw = new StringWriter();
    XmlWriter xw = new XmlTextWriter(sw);

    //- Transform and Output Data ---------------------------------------------------------
    xslTransform.Transform(xr, xw);
    return sw.ToString();
}