string aranan = textBox674.Text.Trim().ToUpper();
for (int i = 0; i <= dataGridView1.Rows.Count - 1; i++)
{
foreach (DataGridViewRow row in dataGridView1.Rows)
{
foreach (DataGridViewCell cell in dataGridView1.Rows.Cells)
{
if (cell.Value != null)
{
if (cell.Value.ToString().ToUpper() == aranan)...