private void button3_Click(object sender, EventArgs e)
        {
            test();
           
        }
        public void releaseObject(object obj)
        {
            try
            {
                System.Runtime.InteropServices.Marshal.FinalReleaseComObject(obj);
                obj = null;
            }
            catch (Exception ex)
            {
                obj = null;
            }
            finally
            {
                GC.Collect();
            }
        }
        public void test()
        {
            dsTest dSet = new dsTest();
            Excel.Application ExcelApp = new Excel.Application();
            Excel.Worksheet ExcelWorkSheet;
            Excel.Workbook ExcelWorkBook;
            Excel.Range ExcelRange;
 
            var workbooks = ExcelApp.Workbooks;
            ExcelWorkBook = workbooks.Open(@"D:\\Эксель.xlsm", 0, false);
            ExcelWorkSheet = ExcelWorkBook.ActiveSheet;
            ExcelRange = ExcelWorkSheet.UsedRange;
 
            for (int Rnum = 2; Rnum <= ExcelRange.Rows.Count - 2; Rnum++)
            {
                DataRow dr = dSet.DataTable1.NewRow();
                for (int Cnum = 1; Cnum <= ExcelRange.Columns.Count; Cnum++)
                {
                    if ((ExcelRange.Cells[Rnum, Cnum] as Excel.Range).Value2 != null)
                    {
                        dr[Cnum - 1] =
            (ExcelRange.Cells[Rnum, Cnum] as Excel.Range).Value2.ToString();
                    }
                }
                dSet.DataTable1.Rows.Add(dr);
                dSet.DataTable1.AcceptChanges();
            }
 
            dataGridView1.DataSource = dSet.DataTable1;
            dataGridView1.Visible = true;
            ExcelWorkBook.Close(true, null, null);
            ExcelApp.Quit();
            releaseObject(ExcelApp);
            releaseObject(workbooks);
            releaseObject(ExcelWorkBook);
            releaseObject(ExcelWorkSheet);
            releaseObject(ExcelRange);
        }

ExcelWorkBook = workbooks.Open(@"D:\\Эксель.xlsm", 0, false);

string fullPath = "D:\\Эксель.xlsm";