/// <summary>
///This method read the document and writes into richtextbox control  
/// </summary>
  
         private voidbtn_Read_Click(objectsender,  EventArgse)
         {
             // call the method to read ms-word document
            ReadMsWord();
         }
/// <summary>
         /// Read ms-word file 
         /// </summary>
         public voidReadMsWord()
         {   
             // variable to store file path
             string filePath=null;
             // open dialog box to select file 
             OpenFileDialog file= new OpenFileDialog();
             // dilog box title name
            file.Title="Word File";
             // set initial directory of computer system
            file.InitialDirectory= "c:\\";
             // set restore directory 
            file.RestoreDirectory= true;
  
             // execute if block when dialog result box click ok button
             if (file.ShowDialog() ==DialogResult.OK)
            {
                 // store selected file path
                filePath=file.FileName.ToString();            
            }
  
             try
            {  
                 // create word application
                 Microsoft.Office.Interop.Word.Applicationword=new Microsoft.Office.Interop.Word.ApplicationClass();
                // create object of missing value
                 object miss= System.Reflection.Missing.Value;
                 // create object of selected file path 
                 object path=filePath;
                 // set file path mode 
                 object readOnly= false;
                 // open document                 
                 Microsoft.Office.Interop.Word.Document docs=word.Documents.Open(refpath, refmiss,  refreadOnly,  refmiss,  refmiss,  refmiss,  refmiss,  refmiss,refmiss,  refmiss,  refmiss,  refmiss,  refmiss,  refmiss,  refmiss,  refmiss);
               // select whole data from active window document
                 docs.ActiveWindow.Selection.WholeStory();
                 // handover the data to cllipboard 
                 docs.ActiveWindow.Selection.Copy();
                 // clipboard create reference of idataobject interface which transfer the data
                 IDataObject data= Clipboard.GetDataObject();
                 //set data into richtextbox control in text format
                 richTextBox2.Text=data.GetData(DataFormats.Text).ToString();
                 // read bitmap image from clipboard with help of iddataobject interface
                 Image img= (Image)data.GetData(DataFormats.Bitmap);
                 // close the document 
                docs.Close(refmiss,  refmiss, refmiss);
            }
             catch (Exception ex) { MessageBox.Show(ex.ToString()); }
            
         }

Step 2: After writing the above code debug the program and click on the Read button

When you click on the Read button then a file dialog box will appear to select an ms-word file, after select a file then press the Open button.

After clicked the open button the following output will appear as follows.