EditItemTemplate Methods...

Some common methods for EditItemTemplate -

protected void Grid_Edit(Object sender, DataGridCommandEventArgs e)
{
Grid.EditItemIndex = e.Item.ItemIndex;
Grid.DataSource = GetDataForGrid();
Grid.DataBind();
}
protected void Grid_Cancel(Object s, DataGridCommandEventArgs e)
{
Grid.EditItemIndex = -1;
Grid.DataSource = GetDataForGrid();
Grid.DataBind();
}

Where GetDataForGrid() method returns DataTable