private void searchButton_Click(object sender, EventArgs e)
        {
            if (String.IsNullOrEmpty(fromPriceTextBox.Text))
            {
                MessageBox.Show("Enter 1st price");
                return;
            }
            if (String.IsNullOrEmpty(toPriceTextBox.Text))
            {
                MessageBox.Show("Enter 2nd price");
                return;
            }

            List <Mobile> mobiles = _mobileManager.GetByPriceRange(fromPriceTextBox.Text, toPriceTextBox.Text);

            if (mobiles != null)
            {
                mobileDataGridView.DataSource = mobiles;
                SL();
                // return;
            }
            else
            {
                MessageBox.Show("No data found");
                return;
            }
        }