Here a quick guide to show you how to reboot a windows computer from C# Its actually really very simple.

With the following code you can create your own User32 class to call windows api directly.

public static class User32
    {
        [DllImport("user32.dll")]
        public static extern bool ExitWindowsEx(ExitWindowsFlags uFlag, UInt32 dwReserved);

        public static bool ExitWindowsEx(ExitWindowsFlags uFlag)
        {
            return ExitWindowsEx(uFlag, 0);
        }
    }

Note: you will also need 'using System.Runtime.InteropServices;' at the top of the C# file. You will probably also want to define all the options that are available to use with the call.

[Flags]
public enum ExitWindowsFlags {
    EWX_LOGOFF = 0,
    EWX_SHUTDOWN = 0x1,
    EWX_REBOOT = 0x2,
    EWX_FORCE = 0x4,
    EWX_POWEROFF = 0x8,
    EWX_FORCEIFHUNG = 0x10,
    EWX_RESTARTAPPS = 0x40
}

The rest is now really simple.

static void Main(string[] args)
{
    if (User32.ExitWindowsEx(ExitWindowsFlags.EWX_REBOOT) == false)
    {   
        Console.WriteLine("FAILED!");
    }
    else
    {
        Console.WriteLine("SUCCESS!");
    }
}