C#

public static class CDDriveControl
{
    public static bool LockMedia(string driveLetter, bool lockDrive)
    {
        bool result = false;
        string fullDrivePath = string.Format(@"\\.\{0}:", driveLetter);
        SECURITY_ATTRIBUTES securityAttributes = new SECURITY_ATTRIBUTES();
        IntPtr hDrive = CreateFile(
            fullDrivePath,
            GENERIC_READ,
            FILE_SHARE_READ | FILE_SHARE_WRITE,
            ref securityAttributes,
            OPEN_EXISTING,
            FILE_ATTRIBUTE_NORMAL,
            IntPtr.Zero);

        if(hDrive != INVALID_HANDLE_VALUE)
        {
            IntPtr outBuffer;
            int bytesReturned;
            NativeOverlapped overlapped = new NativeOverlapped();
            result = DeviceIoControl(
                hDrive,
                IOCTL_STORAGE_MEDIA_REMOVAL,
                ref lockDrive,
                1,
                out outBuffer,
                0,
                out bytesReturned,
                ref overlapped);
            CloseHandle(hDrive);
        }
        return result;
    }

    private const uint GENERIC_READ = 0x80000000;
    private const int FILE_SHARE_READ = 0x00000001;
    private const int FILE_SHARE_WRITE = 0x00000002;
    private const int OPEN_EXISTING = 3;
    private const int FILE_ATTRIBUTE_NORMAL = 0x80;
    private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
    private const int IOCTL_STORAGE_MEDIA_REMOVAL = 0x2D4804;

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern IntPtr CreateFile(
        string lpFileName,
        uint dwDesiredAccess,
        int dwShareMode,
        ref SECURITY_ATTRIBUTES lpSecurityAttributes,
        int dwCreationDisposition,
        int dwFlagsAndAttributes,
        IntPtr hTemplateFile);

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool DeviceIoControl(
        IntPtr hDevice,
        int dwIoControlCode,
        ref bool lpInBuffer,
        int nInBufferSize,
        out IntPtr lpOutBuffer,
        int nOutBufferSize,
        out int lpBytesReturned,
        ref NativeOverlapped lpOverlapped);

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern bool CloseHandle(
        IntPtr hObject);

    [StructLayout(LayoutKind.Sequential)]
    private struct SECURITY_ATTRIBUTES
    {
        int nLength;
        IntPtr lpSecurityDescriptor;
        bool bInheritHandle;
    }
}