How do I serialize a bytearray written as a string so that the byte array can be read later?

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        int i = 0;
        int j = 0;
        Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();

        // Set filter for file extension and default file extension
        dlg.DefaultExt = ".txt";
        dlg.Filter = "Text documents (.txt)|*.txt";

        // Display OpenFileDialog by calling ShowDialog method
        Nullable<bool> result = dlg.ShowDialog();

        // Get the selected file name and display in a TextBox
        if (result == true)
        {
            button2.IsEnabled = true;
            // Open document
            string filename = dlg.FileName;
            try
            {
                using (StreamReader sr = new StreamReader(filename))
                {
                    String line;

                    while ((line = sr.ReadLine()) != null)
                    {
                        if (line.Contains("Vault Serial"))
                        {
                            string[] words = line.Split(':');
                            vault_srno = words[1].Trim();
                            textBox1.Text = vault_srno;
                        }
                        if (line.Contains("Vault Angel Product Key"))
                        {
                            string[] words=line.Split(':');
                            emailnotification_srno = words[1].Trim();
                            textBox2.Text = emailnotification_srno;
                        }
                        if (line.Contains("Number of Licenses"))
                        {
                            string[] words = line.Split(':');
                            number_users = words[1].Trim();
                            textBox3.Text = number_users;
                        }
                        if (line.Contains("License Type"))
                        {
                            string[] words = line.Split(':');
                            lic_type = words[1].Trim();
                            textBox4.Text = lic_type;
                        }
                        if (line.Contains("Vault selected to configure"))
                        {
                            string[] words = line.Split(':');
                            vaults[i,0] = words[1].Trim();
                        }
                        if (line.Contains("Number of Users"))
                        {
                            string[] words = line.Split(':');
                            vaults[i, 1] = words[1].Trim();
                            i++;
                        }
                    }
                }
                while (vaults[j, 0] != null || vaults[j,1]!=null)
                {
                    sb.Append(vaults[j,0]);
                    sb.Append(" ");
                    sb.Append(vaults[j, 1]);
                    sb.Append(" ");
                    /*textBlock1.Text = vaults[j, 0];
                    textBlock1.Text = " ";
                    textBlock1.Text = vaults[j, 1];
                    textBlock1.Text = " ";*/
                    j++;
                }
                textBlock1.Text = sb.ToString();
                /*for (int j = 0; j < vaults.Length/2; j++)
                {
                    MessageBox.Show(vaults[j, 0]);
                    MessageBox.Show(vaults[j, 1]);
                }*/
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }

    private void button2_Click(object sender, RoutedEventArgs e)
    {
        parsefields();
    }
    public string ConvertStringToHex(String input, System.Text.Encoding encoding)
    {
        Byte[] stringBytes = encoding.GetBytes(input);
        StringBuilder sbBytes = new StringBuilder(stringBytes.Length * 2);
        foreach (byte b in stringBytes)
        {
            sbBytes.AppendFormat("{0:X2}", b);

        }
        return sbBytes.ToString();
    }
    private void parsefields()
    {
        int i = 0;
        StringBuilder sb = new StringBuilder();
        byte[] vaultBytes = Encoding.ASCII.GetBytes(vault_srno);
        byte[] emailBytes = Encoding.ASCII.GetBytes(emailnotification_srno);
        byte[] numb_lic = Encoding.ASCII.GetBytes(number_users);
        byte[] type = Encoding.ASCII.GetBytes(lic_type);
        byte[] notif = Encoding.ASCII.GetBytes("VaultSerialNo");
        byte[] notif2 = Encoding.ASCII.GetBytes("EmailNotificationNo");
        byte[] notif3 = Encoding.ASCII.GetBytes("NumberOfLicenses");
        byte[] notif4 = Encoding.ASCII.GetBytes("LicenseType");
        byte[] notif5 = Encoding.ASCII.GetBytes("Vaults");
        /*foreach (byte b in notif)
            sb.Append(b);*/
        foreach (byte b in vaultBytes)
            sb.Append(b);
        sb.Append("/");
        foreach (byte b in notif2)
            sb.Append(b);
        foreach (byte b in emailBytes)
            sb.Append(b);
        sb.Append("/");
        foreach (byte b in notif3)
            sb.Append(b);
        foreach (byte b in numb_lic)
            sb.Append(b);
        sb.Append("/");
        foreach (byte b in notif4)
            sb.Append(b);
        foreach (byte b in type)
            sb.Append(b);
        sb.Append("/");
        foreach (byte b in notif5)
            sb.Append(b);
        while(vaults[i,0]!=null || vaults[i,1]!=null)
        {
            foreach (byte b in vaults[i, 0])
                sb.Append(b);
            sb.Append("-");
            foreach (byte b in vaults[i, 1])
                sb.Append(b);
            sb.Append(",");
            i++;
        }
        unparse(sb.ToString());
        try
        {
            StreamWriter sw = new StreamWriter("C:\\Vault Angel Licences\\VA_" + vault_srno + ".lic");
            sw.WriteLine(sb.ToString());

            sw.Close();
            MessageBox.Show("Vault Angel licence successfully exported to C:\\Vault Angel Licences\\" + vault_srno + ".lic");

        }
        catch
        {
            MessageBox.Show("Error in Saving");
        }
    }
    static byte[] GetBytes(string str)
    {
        byte[] bytes = new byte[str.Length * sizeof(char)];
        System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
        return bytes;
    }
    private void unparse(string ps)
    {
        string[] words = ps.Split('/');
        textBox6.Text = words[0];
        textBox7.Text = words[1];
        textBox8.Text = words[2];
        textBox9.Text = words[3];
        textBox10.Text = words[4];
        //byte[] byteval=new byte[200];
        byte[] value = GetBytes(words[0]);
        //string something = Encoding.ASCII.GetString(words[0]);
    }
}