How to turn on monitor after wake-up from suspend mode? [closed]

Answer 1

Try making the mouse move. When i wake up my Windows 7 system with a tap on the keyboard the screen stays black until i move the mouse.

Cursor.Position = new Point(x, y);

Answer 2

for me it works fine to use pinvoke to call SendMessage.
code example for csharp:

using System;
using System.Runtime.InteropServices;

namespace MyDummyNamespace
{
   class MyProgram
   {
      private static int Main(string[] args)
      {
         // your program code here
         // ...

         NativeMethods.MonitorOff();
         System.Threading.Thread.Sleep(5000);
         NativeMethods.MonitorOn();

         return 0;
      }

      private static class NativeMethods
      {
         internal static void MonitorOn()
         {
            SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (IntPtr)MONITOR_ON);
         }

         internal static void MonitorOff()
         {
            SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (IntPtr)MONITOR_OFF);
         }

         [DllImport("user32.dll", CharSet = CharSet.Auto)]
         private static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);

         private static int MONITOR_ON = -1;
         private static int MONITOR_OFF = 2;
         private static int MONITOR_STANBY = 1;

         private static IntPtr HWND_BROADCAST = new IntPtr(0xffff);
         private static UInt32 WM_SYSCOMMAND = 0x0112;
         private static IntPtr SC_MONITORPOWER = new IntPtr(0xF170);
      }
   }
}

the above solution was inspired by this answer: https://stackoverflow.com/a/332733/1468842