Help!! Excel process keep runnung export excel with Interop

In order to release excel object you need to close workbook object , quit application object and release each com object that us while creating excel file.


please refer link

Releasing Excel after using Interop[^]

You need to close and release the resources after modifying it.
you need to use try finally block and in finally block call app.Quit() method.

public void ExcelMethod()
        {
            Microsoft.Office.Interop.Excel._Application app = new Microsoft.Office.Interop.Excel.Application();
            Microsoft.Office.Interop.Excel._Workbook workbook = app.Workbooks.Add(Type.Missing);
            Microsoft.Office.Interop.Excel._Worksheet worksheet1 = null;
 
            try
            {
                //Microsoft.Office.Interop.Excel._Worksheet worksheet2 = null;
                app.Visible = true;
                worksheet1 = workbook.Sheets["Sheet1"];
                worksheet1 = workbook.ActiveSheet;
                Marshal.ReleaseComObject(workbook);
                Marshal.ReleaseComObject(worksheet1);
 
                worksheet1.Cells[1, 1] = "รางงานการจัดการโครงการโดยการใช้ Program evaluation and review technique";
                worksheet1.Cells[3, 2] = "ตารางแสดงค่าต่างๆของกิจกรรมแต่ละตัวในโครงการนี้";
                Microsoft.Office.Interop.Excel.Range Chartrange = Chartrange = worksheet1.get_Range("A1", "A1");
                ;
                Chartrange.Font.Bold = true;
                GC.Collect();
                Marshal.ReleaseComObject(Chartrange);
                //GC.Collect();

 

                for (int i = 1; i < 7 + 1; i++)
                {
                    worksheet1.Cells[5, i] = dataGridView1.Columns[i - 1].HeaderText;
                    Microsoft.Office.Interop.Excel.Range kk = worksheet1.get_Range("A5", "G5");
                    Microsoft.Office.Interop.Excel.Borders borders = kk.Borders;
                    borders.LineStyle = Microsoft.Office.Interop.Excel.XlLineStyle.xlContinuous;
                    borders.Weight = 3d;
                    GC.Collect();
                    Marshal.ReleaseComObject(borders);
                    Marshal.ReleaseComObject(kk);
 
                }
                for (int i = 0; i < dataGridView1.Rows.Count - 1; i++)
                {
                    for (int j = 0; j < 7; j++)
                    {
                        int excel_cell = dataGridView1.Rows.Count - 1 + 5;
                        if (dataGridView1.Rows[i].Cells[j].Value != null)
                        {
                            int k = i + 6;
                            worksheet1.Cells[i + 6, j + 1] = dataGridView1.Rows[i].Cells[j].Value.ToString();
                            Microsoft.Office.Interop.Excel.Range kk = worksheet1.get_Range("A" + k, "G" + k);
                            Microsoft.Office.Interop.Excel.Borders borders = kk.Borders;
                            borders.LineStyle = Microsoft.Office.Interop.Excel.XlLineStyle.xlContinuous;
                            borders.Weight = 3d;
                            GC.Collect();
                            Marshal.ReleaseComObject(borders);
                            Marshal.ReleaseComObject(kk);
                            //GC.Collect();
                            //GC.WaitForPendingFinalizers();
                        }
                        else
                        {
                            worksheet1.Cells[i + 2, j + 1] = "";
                        }
                    }
                }
            }
            finally
            {
                releaseObject(workbook);
                releaseObject(worksheet1);
 
                if (app != null)
                {
                    app.Quit();
 
                }
                releaseObject(app);
            }
        }
 
        private void releaseObject(object obj)
        {
            if (obj != null && Marshal.IsComObject(obj))
            {
                Marshal.ReleaseComObject(obj);
            }
            obj = null;
        }

[Agent_Spock]
- Added missing code brackets
[Jafarinejajadvazifehkhorani]
-I added one more solution to this question that I mustn't have done it, I should have updated the current answer.