Hi, I have created one application in c#.net.Using this application we can update datagridview,now i need to implement undo in it plz give me some ideas.

 private void button29_Click(object sender, EventArgs e)
    {

           Datatable dt;
          dt.RejectChanges();


    }

using above code i can do undo before updating. but i need a undo feature as in word plz suggest me thanks in advance