void mukerrerkontrol()
        {
            SQLiteConnection baglanti = new SQLiteConnection("Data Source = DB.db");
            baglanti.Open();

            SQLiteCommand komut = new SQLiteCommand("select * from tablomuz where no=@no", baglanti);
            komut.Parameters.AddWithValue("@no", no.Text);
            SQLiteDataReader dr = komut.ExecuteReader();

            if (dr.Read())
            {
                durum = false;
            }
            else
            {
                durum = true;
            }
            baglanti.Close();

        }

private void textBox2_TextChanged(object sender, EventArgs e)
        {
            txtdo.Text = txtdo.Text.ToUpper(); //TÜMÜ BÜYÜK HARF YAPAR
            txtdo.SelectionStart = txtdo.Text.Length; //VE Iİ SORUNUNU ÇÖZER
        }

void siralama()
        {
            SQLiteConnection baglanti = new SQLiteConnection("Data Source = veritabani.db");
            baglanti.Open();
            SQLiteCommand cmd = new SQLiteCommand();
            cmd = new SQLiteCommand("SELECT * FROM tablo ORDER BY no ASC");
            cmd.Connection = baglanti;
            cmd.ExecuteNonQuery();
            baglanti.Close();
            yenile();
        }

Form Load olayında siralama(); çağırıyorum.

Form2 f2 = new Form2();
f2.txt1.Text = lbl1.Text;
f2.combo.text = lbl2.Text; // hatalı satır

using Excel = Microsoft.Office.Interop.Excel;

private void button3_Click(object sender, EventArgs e)
        {
            Microsoft.Office.Interop.Excel.Application uyg = new Microsoft.Office.Interop.Excel.Application();
            uyg.Visible = true;
            Microsoft.Office.Interop.Excel.Workbook kitap = uyg.Workbooks.Add(System.Reflection.Missing.Value);
            Microsoft.Office.Interop.Excel.Worksheet sheet1 = (Microsoft.Office.Interop.Excel.Worksheet)kitap.Sheets[1];
            for (int i = 0; i < dataGridView1.Columns.Count; i++)
            {
                Microsoft.Office.Interop.Excel.Range myRange = (Microsoft.Office.Interop.Excel.Range)sheet1.Cells[1, i + 1];
                myRange.Value2 = dataGridView1.Columns[i].HeaderText;
            }

            for (int i = 0; i < dataGridView1.Columns.Count; i++)
            {
                for (int j = 0; j < dataGridView1.Rows.Count; j++)
                {
                    Microsoft.Office.Interop.Excel.Range myRange = (Microsoft.Office.Interop.Excel.Range)sheet1.Cells[j + 2, i + 1];
                    myRange.Value2 = dataGridView1[i, j].Value;
                }
            }
        }

void verigetir()
        {
            baglanti = new SQLiteConnection("Data Source = datadb.db");
            baglanti.Open();
            da = new SQLiteDataAdapter("SELECT *FROM data", baglanti);
            DataTable tablo = new DataTable();
            da.Fill(tablo);
            dataGridView1.DataSource = tablo;
            baglanti.Close();
            dataGridView1.CurrentCell = dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells[1];//enalt seçiyor
            dataGridView1.FirstDisplayedScrollingRowIndex = dataGridView1.RowCount - 1;//en alta gdiyor
            dataGridView1[0, dataGridView1.RowCount - 1].Selected = true;//en alta gidiyor
            datarenk();
        }

void datarenk()
        {
            for (int i = 0; i < dataGridView1.Rows.Count - 1; i++)
            {
                DataGridViewCellStyle renk = new DataGridViewCellStyle();
                if (Convert.ToString(dataGridView1.Rows[i].Cells[1].Value) == "EVET")
                {

                    renk.BackColor = Color.Red;
                    renk.ForeColor = Color.White;
                }

                dataGridView1.Rows[i].DefaultCellStyle = renk;

            }
        }

private void button2_Click(object sender, EventArgs e)
        {
            //textBox1.Text = textBox1.Text.ToUpper(); //TÜMÜ BÜYÜK HARF YAPAR
            //textBox1.SelectionStart = textBox1.Text.Length; //VE Iİ SORUNUNU ÇÖZER
            
            baglanti.Open();
            DataTable tbl = new DataTable();
            SQLiteDataAdapter ara1 = new SQLiteDataAdapter("select * from data where alan1 like '%" + textBox1.Text + "%'", baglanti);
            SQLiteDataAdapter ara2 = new SQLiteDataAdapter("select * from data where alan2 like '" + textBox1.Text + "' ", baglanti);
            SQLiteDataAdapter ara3 = new SQLiteDataAdapter("select * from data where alan3 like '%" + textBox1.Text + "%'", baglanti);
            SQLiteDataAdapter ara4 = new SQLiteDataAdapter("select * from data where alan4 like '" + textBox1.Text + "' ", baglanti);
            ara1.Fill(tbl);
            ara2.Fill(tbl);
            ara3.Fill(tbl);
            ara4.Fill(tbl);
            baglanti.Close();
            dataGridView1.DataSource = tbl;
            datarenk();
		}