Passing of selected value of gridview to another page to textbox using button of gridview .

Anil LinkButton and Button in this factor has only one difference which is the type, one is LinkButton and one is Button. So what ever code you are writing in LinkButton write the same code in Button, just change if there is any LinkButton typecasting to Button.

And now the main issue,to send value of the selected row's text box value. If you can get it then you can also send it to another textbox. So use RowCommand event of GridView and within that catch the button click with CommandName/CommandValue of Button or LinkButton. And then with the help of FindControl function get the value of either TextBox or Label or any other controls. Take a look on the code bellow.

string Ques = ((TextBox)GridViewFRM.Rows[i].FindControl("GVQuestionTextBox")).Text; 

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
   {
        if (e.CommandName == "More")
        {
            string Ques = ((TextBox)GridViewFRM.Rows[i].FindControl("GVQuestionTextBox")).Text; 
        }
    }