public class testForm:Form
{
...
...
public void test()
{
        System.Windows.Forms.MethodInvoker CallToRefreshGrid = new System.Windows.Forms.MethodInvoker (this.RefreshGrid);
        this.BeginInvoke(CallToRefreshGrid);
   
}

private void RefreshGrid()
  {
   dataGrid1.DataSource = appData.Tables[0].DefaultView;
   dataGrid1.Refresh();
  }

}