PersianCalendar pc = new PersianCalendar();

 DateTime dt1 = pc.ToDateTime(int.Parse(comyear.Text), int.Parse(commonth.Text), int.Parse(comday.Text), 0, 0, 0, 0);
                DateTime dt2 = pc.ToDateTime(int.Parse(comyear1.Text), int.Parse(commonth1.Text), int.Parse(comday1.Text), 0, 0, 0, 0);
                var search = from a in context.nametabel
                             where  (a.tarikh >= dt1 && a.tarikh <= dt2)
                             select a;
                    

                dataGridView1.DataSource = search;