Populate textBoxes with database rows selected from Comboboxel

Hello. I need to insert 5 strings in my TextBoxes that values is stored in database. From Database values is populated to Combobox. But I cannot to populate from combobox to textboxes

This Code was working in Windows Forms, but not worked in WPF

 private void fillCombobox()
        {
            string querry = "Select * from Persons";
            SqlCeCommand cmd = new SqlCeCommand(querry, cn);
            SqlCeDataAdapter da = new SqlCeDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds, "Persons");
            DataTable dt = ds.Tables["Persons"];
            int i;
            for (i = 0; i <= dt.Rows.Count - 1; i++)
            {
                if (!comboBox1.Items.Contains(dt.Rows[i].ItemArray[0]))
                {
                    comboBox1.Items.Add(dt.Rows[i].ItemArray[0]);

                }

            }

            cn.Close();
            comboBox1.Text = "Selecting persons here";
            pictureBox1.Image = null;
            textBox2.Text = "";
            textBox3.Text = "";
            textBox4.Text = "";
            textBox5.Text = "";
            textBox6.Text = "";
        }


        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            cn.Open();
            string querry = "select * from Persons where Name='" + comboBox1.Text.Trim() + "'";
            SqlCeCommand cmd = new SqlCeCommand(querry, cn);
            SqlCeDataReader reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                textBox2.Text = reader["Name"].ToString();
                textBox3.Text = reader["Surname"].ToString();
                textBox4.Text = reader["Phone"].ToString();
                textBox5.Text = reader["Mail"].ToString();
                textBox6.Text = reader["Address"].ToString();
             }
            cn.Close();
            reader.Close();
        }