Балуемся индикаторами NumLock, CapsLock, ScrollLock на клавиатуре!

using System.Runtime.InteropServices;
using System.Threading;

private const byte VK_SCROLL = 0x91;
private const byte VK_NUMLOCK = 0x90;
private const byte VK_CAPITAL = 0x14;
private const uint KEYEVENTF_KEYUP = 0x2;


[DllImport("user32.dll", EntryPoint = "keybd_event", SetLastError = true)]
static extern void keybd_event(byte bVk, byte bScan, uint dwFlags, uint dwExtraInfo);

[DllImport("user32.dll", EntryPoint = "GetKeyState", SetLastError = true)]
static extern short GetKeyState(uint nVirtKey);
//Scroll-------------------------------------------------------
public static void SetScrollLockKey(bool newState)
{
    bool scrollLockSet = GetKeyState(VK_SCROLL) != 0;
    if (scrollLockSet != newState)
    {
        keybd_event(VK_SCROLL, 0, 0, 0);
        keybd_event(VK_SCROLL, 0, KEYEVENTF_KEYUP, 0);
    }
}
public static bool GetScrollLockState()
{
    return GetKeyState(VK_SCROLL) != 0;
}
//NUM------------------------------------------------------- 
public static void SetNumLockKey(bool newState)
{
    bool scrollLockSet = GetKeyState(VK_NUMLOCK) != 0;
    if (scrollLockSet != newState)
    {
        keybd_event(VK_NUMLOCK, 0, 0, 0);
        keybd_event(VK_NUMLOCK, 0, KEYEVENTF_KEYUP, 0);
    }
}

public static bool GetNumLockState()
{
    return GetKeyState(VK_NUMLOCK) != 0;
}
//Caps-------------------------------------------------------
public static void SetCapsLockKey(bool newState)
{
    bool scrollLockSet = GetKeyState(VK_NUMLOCK) != 0;
    if (scrollLockSet != newState)
    {
        keybd_event(VK_CAPITAL, 0, 0, 0);
        keybd_event(VK_CAPITAL, 0, KEYEVENTF_KEYUP, 0);
    }
}

public static bool GetCapsLockState()
{
    return GetKeyState(VK_CAPITAL) != 0;
}

SetNumLockKey(true);
Thread.Sleep(100);
SetNumLockKey(false);
Thread.Sleep(100);
SetCapsLockKey(true);
Thread.Sleep(100);
SetCapsLockKey(false);
Thread.Sleep(100);
SetScrollLockKey(true);
Thread.Sleep(100); 
SetScrollLockKey(false);
Thread.Sleep(100); 

SetNumLockKey(true);

SetNumLockKey(false);