using System;                     

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

using System.Web.UI;

using System.Xml.Linq;

//using Microsoft.Office.Interop.Word;

//using TinyMCE_Integration_MVC.Models;

​

using System.IO;

using System.Text;

using DocumentFormat.OpenXml.Packaging;

using DocumentFormat.OpenXml.Wordprocessing;

using DocumentFormat.OpenXml;

using Microsoft.Office.Interop.Word;

//using Document = DocumentFormat.OpenXml.Wordprocessing.Document;

//using SampleViewModel;

using System.Text.RegularExpressions;

using DocumentFormat.OpenXml.Office2010.Word;

using DocumentFormat.OpenXml.ExtendedProperties;

using System.Runtime.InteropServices.ComTypes;

 using System.Drawing;

 using Spire.Doc;

 using Spire.Doc.Documents;

 using Spire.Doc.Fields;

 using Document = Spire.Doc.Document;

 using Paragraph = Spire.Doc.Documents.Paragraph;

namespace HelloWorldMvcApp.Controllers

{

    public class HomeController : Controller

    {

        [HttpGet]

        public ActionResult Index()

        {

            SearchAndReplace();

            return View(new SampleViewModel());

        }

​

​

         public static void SearchAndReplace()

    {

    string filename = @"C:\Users\anujrsin\OneDrive - Capgemini\Attachments\test.docx";

        //string filename = @"C:\Anuj\test.docx";

        Document document1 = new Document();

        document1.LoadFromFile(filename);

​

        TextSelection[] selections1 = document1.FindAllString("Test2", true, true);

        //Here in first parameter you need pass the string which you want to replace.

        foreach (TextSelection selection1 in selections1)

        {

            TextRange range1 = selection1.GetAsOneRange();

            Paragraph paragraph = range1.OwnerParagraph;

            int index1 = paragraph.ChildObjects.IndexOf(range1);

            paragraph.AppendHTML("<b>Hello</b>");

            range1.OwnerParagraph.ChildObjects.Remove(range1);

        }

        document1.SaveToFile(filename, FileFormat.Docx);

    }

    }

}