for (int i = 0; i < dataGridView1.Rows.Count; i++)

                {

                    if (dataGridView1.Rows[i].Cells["Make"].Value.ToString().ToUpper().Contains("ro"))

                    {

                        dataGridView1.Rows[i].Cells["Make"].Style = new DataGridViewCellStyle() { Font = new Font(dataGridView1.Font, FontStyle.Bold), ForeColor = Color.DodgerBlue };

//it will change cell forecolor you can use according to you required action

// same like forecolor you can change backcolor or cell and also row.

                    }

//ro 

// or you can use textbox value.

                    if (dataGridView1.Rows[i].Cells["Model"].Value.ToString().ToUpper().Contains(txtBox1.Text))

                    {

                        dataGridView1.Rows[i].Cells["Model"].Style = new DataGridViewCellStyle() { Font = new Font(dataGridView1.Font, FontStyle.Bold), ForeColor = Color.DodgerBlue };

 

// for full row colors you can use following

// dataGridView1.Rows[i].DefaultCellStyle = new DataGridViewCellStyle() { Font = new Font(dataGridView1.Font, FontStyle.Bold), ForeColor = Color.DodgerBlue, BackColor = Color.Green };

                    }                   

}