Magnitude and phase spectrum of sine wave using FFT

I want to display the magnitude and phase spectrum of a signal data using the code below.

	load("sec2Harmonics.mat")

	Length = numel(x) % The number of elements
	fs = 44100;

	amp = 1000;	% Amplitude (coefficient)


 	Plength = Length;
	plot(x(1:Plength));	% Plot graph


	FFT_len = 1024;  % 1024 points;
	plot_FFT_len = FFT_len/2; 
 	d_proc1 = x(1:FFT_len);

	win = ????? 

	d_proc2 = ?????;

	fftd = fft(d_proc2);

	delta_f = fs/FFT_len;
	n = 0:1:FFT_len-1;
	w = delta_f*n;

       plot(w(1:plot_FFT_len), 20*log10(abs(?????))(1:plot_FFT_len));

Ive tried to replace the '?????' as below but when I run the code it only display the sine wave. Theres no error on the command window I dont know what is wrong and what should be fixed. Please help me.

       Length = numel(x) % The number of elements
	fs = 44100;

	amp = 1000;	% Amplitude (coefficient)


 	Plength = Length;
  subplot(2,1,1);
	plot(x(1:Plength));	% Plot graph
  

	FFT_len = 512;  % 512 points;
	plot_FFT_len = FFT_len/2; 
 	d_proc1 = x(1:FFT_len);

	win = 0.5 - 0.5*cos(2*pi*linspace(0, 1, n));
  win = (Plength);
	d_proc2 = x.*win;

	fftd = fft(d_proc2);

	delta_f = fs/FFT_len;
	n = 0:1:FFT_len-1;
	w = delta_f*n;

  subplot(2,1,2);  
  plot(w(1:plot_FFT_len), 20*log10(abs(fft/Plength))(1:plot_FFT_len));

This is the display result that I got.