I just added g.drawRect to your paint method, I think it's obvious why it's not working if you try this code
Code:
	@Override
	public void paint(final Graphics g)
	{
		int xt = 0;
		int row;
		int col;
		int x, y;
		for (row = 0; row < IMAGES; row++)
			for (col = 0; col < IMAGES; col++)
			{
				x = col * IMAGES;
				y = row * IMAGES;
				// if((row % 1) == (col % 1))
				// g.drawImage(cards[col][col], xt, 0, this);
				g.drawRect(x, y, 100, 100);
				xt += cards[row][row].getWidth(null) + 10;
				xt += cards[col][col].getHeight(null) + 10;
				// cards[i][i] = (int) (Math.random()*5);
				// if((row % 2) == (col % 2))
				// g.drawImage(cards[col][col], xt, 0, this);
				// xt+=cards[col][col].getWidth(null) + 10;
			}
	}