C#

using iTextSharp.text;
using iTextSharp.text.pdf;

 var baseUrl = SecurityContext.BaseUrl;

string urlString = string.Format("{1}Downloads/SalesOrderInvoice.aspx?id={0}", OrderId, baseUrl);

                   Uri url = new Uri(urlString);

                   IDownloader htmlToPDFDownloader = new HtmlToPDFDownloader(url);

                   string fileName = string.Format("Invoice for Order Referecne. {0}", OrderCode);

                   htmlToPDFDownloader.Download(fileName);

public interface IDownloader
    {
        object GetDownloadable();

        void Download(string fileName);
    }

using iTextSharp.text.pdf;
using iTextSharp.text.pdf.draw;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text.RegularExpressions;
using System.Web;
namespace sampleproj.Client
{
    public class HtmlToPDFDownloader : IDownloader
    {
        private string htmlString;

        public HtmlToPDFDownloader(string htmlString)
        {
            this.htmlString = htmlString;
        }

        private string ImageToBase64(string url)
        {
            WebClient client = new WebClient();
            byte[] bytes ;
            if(url.StartsWith("http"))
            {
                bytes = client.DownloadData(url);
            }
            else
            {
                string physicalPath = HttpContext.Current.Server.MapPath(string.Format("~{0}", url));
                bytes = File.ReadAllBytes(physicalPath);                
            }

            string base64String = Convert.ToBase64String(bytes);

            return "data:image/png;base64," + base64String;
        }

        //private string GetDownloadedContent(Uri url)
        //{   
        //    HttpWebRequest webrequest = (HttpWebRequest)WebRequest.Create(url);
            
        //    webrequest.Method = "GET";

        //    webrequest.ContentType = "text/html";

        //    HttpWebResponse webresponse = (HttpWebResponse)webrequest.GetResponse();

        //    Stream stream = webresponse.GetResponseStream();

        //    StreamReader r = new StreamReader(stream);

        //    return r.ReadToEnd();
        //}

        public HtmlToPDFDownloader(Uri url)
        {
            WebClient client = new WebClient();

            client.Headers.Add("_uidqqweb4324", ConfigurationManager.UserId);

            this.htmlString = client.DownloadString(url);

            //this.htmlString = GetDownloadedContent(url);

            foreach (Match m in Regex.Matches(htmlString, "<img.+?src=[\"'](.+?)[\"'].+?>", RegexOptions.IgnoreCase | RegexOptions.Multiline))
            {
                string src = m.Groups[1].Value;

                //string locaPath = new Uri(src).LocalPath;

                //string physicalPath = HttpContext.Current.Server.MapPath(string.Format("~{0}", locaPath));

                //htmlString = htmlString.Replace(src, physicalPath);

                //string src = m.Groups[1].Value;

                //string locaPath = new Uri(src).ToString();
                //locaPath = HttpContext.Current.Server.MapPath(locaPath);
                string physicalPath = ImageToBase64(src); //Server.MapPath(string.Format("~{0}",locaPath));

                htmlString = htmlString.Replace(src, physicalPath);
            }
        }


        private byte[] GetStream()
        {
            MemoryStream stream = new MemoryStream();

            var htmlContent = this.htmlString;

            var converter = new NReco.PdfGenerator.HtmlToPdfConverter();

            converter.Margins = new NReco.PdfGenerator.PageMargins
            {
                Bottom = 5,
                Left = 2.5f,
                Right = 2.5f,
                Top = 5
            };

            var pdfBytes = converter.GeneratePdf(htmlContent);

            return pdfBytes;
        }

        public object GetDownloadable()
        {
            return GetStream();
        }

        public void Download(string fileName)
        {
            var pdfBytes = GetStream();

            HttpContext.Current.Response.Clear();
            HttpContext.Current.Response.ContentType = "application/pdf; file";
            HttpContext.Current.Response.AddHeader("content-length", pdfBytes.Length.ToString());

            fileName = fileName + "_" + DateTime.Now.ToString("ddMMMyyy") + ".pdf";

            HttpContext.Current.Response.AddHeader("content-disposition", "attachment;" + "filename=" + fileName);
            HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);

            HttpContext.Current.Response.BinaryWrite(pdfBytes);
            HttpContext.Current.Response.Flush();
            HttpContext.Current.Response.Close();
            HttpContext.Current.Response.End();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace EnergyEngineers.Client
{
    public class SecurityContext
    {
        public int CurrentUserId
        {
            get
            {
                return 1;
            }
        }

        public static string BaseUrl
        {
            get
            {
                return HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Authority) + HttpRuntime.AppDomainAppVirtualPath;
            }
        }
    }
}

if (timer1.Enabled)
{
    MessageBox.Show("Sorry you have already started the Timer");
}

else
     timer1.Start();
     this.StopWatch.Start();

if (timer1.Enabled)
{
    MessageBox.Show("Sorry you have already started the Timer");
}
else
{
     timer1.Start();
     this.StopWatch.Start();
}