how to convert a illegible string to legible string?

Try this


        private void button1_Click(object sender, EventArgs e)
        {
            string encoded_text = richTextBox1.Text;
            string decoded_text="";
            byte[] b = System.Text.Encoding.UTF8 .GetBytes(encoded_text);
            foreach (byte element in b )
            {
                decoded_text += element;
            }
           richTextBox2.Text =decoded_text  ;
        }