Could you debug it and paste some useful debug messages to me ?
protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
GridView1.EditIndex = e.NewEditIndex;
GridView1.DataBind();
}
void Bind()
{
SqlDataAdapter da = new SqlDataAdapter("select * from emp", conn);
DataSet ds = new DataSet();
da.Fill(ds, "emp");
GridView1.DataSource = ds.Tables[0];
GridView1.DataBind();
conn.Close();
}