C# Select random, unique, images from folder on button click

I'm working on a C# card game where I want images to be randomly selected on a button click. Once a card has been chosen, it has to be displayed to the user, and something has to happen so it can't be selected again. I got the first part down, a random image is selected and is shown to the user, but I can't make it so it can't be selected again. Sometimes a card is picked multiple times, sometimes no image is selected at all and I get the error image. This is the code so far.

public partial class Form1 : Form
    {
        private List<int> useableNumbers;

        public Form1()
        {
            InitializeComponent();
            // Creates a list of numbers (card names) that can be chosen from
            useableNumbers = new List<int>{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,
                                          35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54};
            settings = new Settings();
        }

        private void btnDrawCard_Click(object sender, EventArgs e)
        {
            this.setImage();
        }

        private void setImage()
        {
            // Checks if there are still numbers left in the List
            if (useableNumbers.Count() == 0)
            {
                MessageBox.Show("The game has ended");
                Application.Exit();
            }
            else
            {
                Random r = new Random();
                int i = r.Next(useableNumbers.Count());
                // Looks for the path the executable is in
                string path = System.IO.Path.GetDirectoryName(Application.ExecutablePath) + @"\images\";
                // Looks up the image in the images folder, with the name picked by the Random class and with the extension .png
                string image = path + i + ".png";
                // Sets the image in the pictureBox as the image looked up
                pictureBox1.ImageLocation = image;
                // Removes the selected image from the List so it can't be used again
                useableNumbers.RemoveAt(i);
            }
        }

        private void quitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void settingsToolStripMenuItem_Click(object sender, EventArgs e)
        {
            settings.Show();
        }

To clarify it a little bit; I have a folder called 'images' in the same folder as the executable. Inside that folder, there are 54 images named '1' to '54' (52 normal cards and two jokers). The numbers in the useableNumbers List represent the imagenames inside that folder. When an image is selected, I want to remove that image's name from the List with useableNumbers.RemoveAt(i);. Although I do get the message 'The game has ended', I also get the aforementioned problems.

I feel like the useableNumbers.RemoveAt(i); doesn't change the indexes of the List, so when, say, '10' gets deleted, it keeps an index of 11 in stead of moving all values down by one, if you know what I mean.

I've also tried storing the images in a List, but couldn't get that to work either so that's why I did it like this. Still new to C#, so maybe there are better ways of doing it.

How can I fix the removing from the list, so I don't get the same image twice or more, or no image at all?