Перезагрузите компьютер из приложения C#/WPF.

Попробуй это:

System.Diagnostics.Process.Start("shutdown.exe", "-r -t 0");

Это запускает встроенный в Windows инструмент shutdown, который также может выключать или выходить из системы на удаленном или локальном компьютере.

Вот полный список опций с сайта ss64.com:

Syntax

      SHUTDOWN [logoff_option]  [/m \\Computer] [options]

logoff_option:
    /i         Display the GUI (must be the first option)
    /l         Log off. This cannot be used with /m or /d option
    /s         Shutdown
    /r         Shutdown and Restart
    /a         Abort a system shutdown.
               (only during the time-out period)
    /p         Turn off the local computer with no time-out or warning
               (only with /d)
    /h         Hibernate the local computer (only with /f )
    /e         Document the reason for an unexpected shutdown of a computer

Options:

   /m \\Computer  : A remote computer to shutdown.

   /t:xxx         : Time until system shutdown in seconds. 
                    The valid range is xxx=0-600 seconds. [default=30]
   /c "Msg"       : An optional shutdown message [Max 127 chars]

   /f             : Force running applications to close.
                    This will not prompt for File-Save in any open applications.
                    so will result in a loss of all unsaved data!!!

   /d u:xx:yy     : List a USER reason code for the shutdown. 
   /d P:xx:yy     : List a PLANNED reason code for the shutdown.
                     xx Specifies the major reason code (0-255)
                     yy Specifies the minor reason code (0-65536)

Вы, наверное, заметили, что я использовал стиль Linux/UNIX для передачи аргументов командной строки (используя знак '-'). В Windows соглашение использует '/'. Это не имеет значения - программе все равно.

Вы можете использовать ExitWindowsEx API. С pinvoke.net

[Flags]
public enum ExitWindows : uint
{
   // ONE of the following five:
   LogOff = 0x00,
   ShutDown = 0x01,
   Reboot = 0x02,
   PowerOff = 0x08,
   RestartApps = 0x40,
   // plus AT MOST ONE of the following two:
   Force = 0x04,
   ForceIfHung = 0x10,
}

[Flags]
enum ShutdownReason : uint
{
    MajorApplication = 0x00040000,
    MajorHardware = 0x00010000,
    MajorLegacyApi = 0x00070000,
    MajorOperatingSystem = 0x00020000,
    MajorOther = 0x00000000,
    MajorPower = 0x00060000,
    MajorSoftware = 0x00030000,
    MajorSystem = 0x00050000,

    MinorBlueScreen = 0x0000000F,
    MinorCordUnplugged = 0x0000000b,
    MinorDisk = 0x00000007,
    MinorEnvironment = 0x0000000c,
    MinorHardwareDriver = 0x0000000d,
    MinorHotfix = 0x00000011,
    MinorHung = 0x00000005,
    MinorInstallation = 0x00000002,
    MinorMaintenance = 0x00000001,
    MinorMMC = 0x00000019,
    MinorNetworkConnectivity = 0x00000014,
    MinorNetworkCard = 0x00000009,
    MinorOther = 0x00000000,
    MinorOtherDriver = 0x0000000e,
    MinorPowerSupply = 0x0000000a,
    MinorProcessor = 0x00000008,
    MinorReconfig = 0x00000004,
    MinorSecurity = 0x00000013,
    MinorSecurityFix = 0x00000012,
    MinorSecurityFixUninstall = 0x00000018,
    MinorServicePack = 0x00000010,
    MinorServicePackUninstall = 0x00000016,
    MinorTermSrv = 0x00000020,
    MinorUnstable = 0x00000006,
    MinorUpgrade = 0x00000003,
    MinorWMI = 0x00000015,

    FlagUserDefined = 0x40000000,
    FlagPlanned = 0x80000000
}

[DllImport("user32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool ExitWindowsEx(ExitWindows uFlags, ShutdownReason dwReason);

И использовать его:

ExitWindowsEx(
  ExitWindows.Reboot,
  ShutdownReason.MajorOther | ShutdownReason.MinorOther | ShutdownReason.FlagPlanned
); 

Альтернативой может быть использование WMI (т. е. пространства имен System.Management); Google предлагает варианты этого кода —

  ManagementClass W32_OS = new ManagementClass("Win32_OperatingSystem")
  ManagementBaseObject inParams, outParams;
  int result;
  W32_OS.Scope.Options.EnablePrivileges = true;

  foreach(ManagementObject obj in W32_OS.GetInstances())
  {
    inParams = obj.GetMethodParameters("Win32Shutdown");
    inParams["Flags"] = 6; //ForcedReboot; -- fixed to restart rather than shutdown
    inParams["Reserved"] = 0;

    outParams = obj.InvokeMethod("Win32Shutdown", inParams, null)
    result = Convert.ToInt32(outParams["returnValue"]);
    if (result !=0) throw new Win32Exception(result);
  }

Рабочий код внутри службы Windows:

var cmd = new System.Diagnostics.ProcessStartInfo("shutdown.exe", "-r -t 0");
cmd.CreateNoWindow = true;
cmd.UseShellExecute = false;
cmd.ErrorDialog = false;
System.Diagnostics.Process.Start(cmd);