unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Buttons;

type
  TForm1 = class(TForm)
    SpeedButton1: TSpeedButton;
    SpeedButton2: TSpeedButton;
    SpeedButton3: TSpeedButton;
    procedure SpeedButton2Click(Sender: TObject);
    procedure SpeedButton1Click(Sender: TObject);
    procedure SpeedButton3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

type
TKeyType = (ktCapsLock, ktNumLock, ktScrollLock);

procedure SetLedState(KeyCode: TKeyType; bOn: Boolean);
var
KBState: TKeyboardState;
Code: Byte;
begin
  case KeyCode of
  ktScrollLock: Code:=VK_SCROLL;
  ktCapsLock:   Code:=VK_CAPITAL;
  ktNumLock:    Code:=VK_NUMLOCK;
  end;
GetKeyboardState(KBState);
if (Win32Platform = VER_PLATFORM_WIN32_NT) then
begin
  if Boolean(KBState[code]) <> bOn then
  begin
  keybd_event(Code,MapVirtualKey(Code, 0),KEYEVENTF_EXTENDEDKEY,0);
  keybd_event(Code,MapVirtualKey(Code, 0),KEYEVENTF_EXTENDEDKEY or KEYEVENTF_KEYUP,0);
  end;
end
else
  begin
  KBState[code] := Ord(bOn);
  SetKeyboardState(KBState);
  end;
end;
//-------------
var
  a,b,c:boolean;
{$R *.dfm}

procedure TForm1.SpeedButton1Click(Sender: TObject);
begin
if not a then begin
  SetLedState(ktCapsLock, True); // CapsLock on
  a:=not(a);
end
else begin
  SetLedState(ktCapsLock, False); // CapsLock off
  a:=not(a);
end;
end;

procedure TForm1.SpeedButton2Click(Sender: TObject);
begin
if not b then begin
  SetLedState(ktNumLock, True); // NumLock on
  b:=not(b);
end
else begin
  SetLedState(ktNumLock, False); // NumLock off
  b:=not(b);
end;
end;

procedure TForm1.SpeedButton3Click(Sender: TObject);
begin
if not c then begin
  SetLedState(ktScrollLock, True); // ScrollLock on
  c:=not(c);
end
else begin
  SetLedState(ktScrollLock, False); // ScrollLock off
  c:=not(c);
end;
end;

end.