C# 如何实现u盘检测，有程序正常运行，没有程序进行提示

[沧海1梦]

如题，想实现类似加密狗的功能，如果程序检测到有U盘插入，整个程序正常运行，如果没有，则程序提示请插入U盘，
C#加wpf，以下是我写的，但是msg传递有问题，请大家帮忙看看

  private void Win_Load(object sender, RoutedEventArgs e)
        {
            System.Windows.Interop.HwndSource hWndSource;
            System.Windows.Interop.WindowInteropHelper wih = new System.Windows.Interop.WindowInteropHelper(this);
            hWndSource = System.Windows.Interop.HwndSource.FromHwnd(wih.Handle);
            //添加处理程序 
            hWndSource.AddHook(winmsg);
        }

        public const int WM_DEVICECHANGE = 0x219;
        public const int DBT_DEVICEARRIVAL = 0x8000;    //如果m.Msg的值为0x8000那么表示有U盘插入
        public const int DBT_CONFIGCHANGECANCELED = 0x0019;
        public const int DBT_CONFIGCHANGED = 0x0018;
        public const int DBT_CUSTOMEVENT = 0x8006;
        public const int DBT_DEVICEQUERYREMOVE = 0x8001;
        public const int DBT_DEVICEQUERYREMOVEFAILED = 0x8002;
        public const int DBT_DEVICEREMOVECOMPLETE = 0X8004;
        public const int DBT_DEVICEREMOVEPENDING = 0x8003;
        public const int DBT_DEVICETYPESPECIFIC = 0x8005;
        public const int DBT_DEVNODES_CHANGED = 0x0007;
        public const int DBT_QUERYCHANGECONFIG = 0x0017;
        public const int DBT_USERDEFINED = 0xFFFF;
        private IntPtr winmsg(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {

           try
           {
               switch (msg)
               {
                   case WM_DEVICECHANGE:
                       break;
                   case DBT_DEVICEARRIVAL://U盘插入
                       string[] strDrivers = Environment.GetLogicalDrives();
                       break;
                   case DBT_CONFIGCHANGECANCELED:
                       break;
                   case DBT_CONFIGCHANGED:
                       break;
                   case DBT_CUSTOMEVENT:
                       break;
                   case DBT_DEVICEQUERYREMOVE:
                       break;
                   case DBT_DEVICEQUERYREMOVEFAILED:
                       break;
                   case DBT_DEVICEREMOVECOMPLETE:   //U盘卸载
                       break;
                   case DBT_DEVICEREMOVEPENDING:
                       break;
                   case DBT_DEVNODES_CHANGED:
                       break;
                   case DBT_QUERYCHANGECONFIG:
                       break;
                   case DBT_USERDEFINED:
                       break;
                   default:
                       break;
               }
           }
           catch (System.Exception ex)
           {
               log.Error("U盘检测：" + ex);
           }
           return IntPtr.Zero;
        }