JTextArea not showing

Why JTextArea not showing in GUI ?

public class AddMovie extends JTextField {

    static JFrame frame;
    private JLabel description;
    JTextArea movieDescription;

    public JPanel createContentPane() throws IOException
    {

        JPanel totalGUI = new JPanel();
        totalGUI.setLayout(null);
        totalGUI.setBackground(Color.WHITE);

        description = new JLabel("Description  ");
            description.setLocation(15,285);
            description.setSize(120, 25);
            description.setFont(new java.awt.Font("Tahoma", 0, 12));
            movieDescription=new JTextArea();
          movieDescription.setLocation(15,320);
          movieDescription.setSize(420, 110);

        JScrollPane scrollPane = new JScrollPane(movieDescription);    
        totalGUI.add(description);
        totalGUI.add(movieDescription);
        totalGUI.add(cancel);
        totalGUI.add(scrollPane);                   
        return totalGUI;
    }


    static void createAndShowGUI() throws IOException
    {

        JFrame.setDefaultLookAndFeelDecorated(true);
        frame = new JFrame("New Movie");
        //Create and set up the content pane.
        AddMovie demo = new AddMovie();
        frame.setContentPane(demo.createContentPane());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(515, 520);
        frame.setLocation(480,120);
        frame.setVisible(true);
    }

    public void setVisible(boolean b) {
        // TODO Auto-generated method stub

    }

}

As suggested here and here, a null layout invites trouble. Because your display centers on the description, use the JTextArea constructor that lets you specify a size in rows and columns. When you pack() the enclosing Window, it will be resized to fit the text area. I've added some ad hoc text to illustrate the effect. I've also updated the code to allow the text area to grow when resizing the frame.

import java.awt.EventQueue;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

/**
 * @see https://stackoverflow.com/a/38282886/230513
 */
public class Test {

    private JPanel createPanel() {
        JPanel panel = new JPanel(new GridLayout());
        //panel.setBorder(BorderFactory.createTitledBorder("Description"));
        JTextArea movieDescription = new JTextArea(10, 20);
        panel.add(new JScrollPane(movieDescription));
        movieDescription.setLineWrap(true);
        movieDescription.setWrapStyleWord(true);
        movieDescription.setText(movieDescription.toString());
        return panel;
    }

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setContentPane(createPanel());
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Test()::display);
    }
}