if you want the row number of the DataGrid, handle MouseUp event:private void dataGrid1_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e) 

     System.Drawing.Point pt = new Point(e.X, e.Y); 
     DataGrid.HitTestInfo hti = dataGrid1.HitTest(pt); 
     if(hti.Type == DataGrid.HitTestType.Cell) 
     { 
          MessageBox.Show(hti.Row.ToString());
     } 

 or try
dataGrid1.CurrentRowIndexorCurrencyManager cm;
cm=(CurrencyManager)YourDataGrid.BindingContext[YourDataGrid.DataSource];
DataRowView drv;
drv =(DataRowView) cm.Current;
DataRow myDataRow = drv.Row;