You can use the Windows API function EnumDisplaySettings() to get a list of valid mode settings, and use the Windows API function ChangeDisplaySettings() to actually change the display setting. Note that many drivers will not perform the reset without rebooting the computer, even though they are capable of doing so.

Example:
unit Unit ;
interface
uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Spin;
type
  PdmArray = ^TDmArray;
  TDmArray = array[0..0] of TDeviceMode;
type
  TForm  = class(TForm)
    Memo : TMemo;
    SpinEdit : TSpinEdit;
    Button : TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button Click(Sender: TObject);
  private
    lpDmArray : PDmArray;
    NumModes : integer;
    { Private declarations }
  public
    { Public declarations }
  end;
var
  Form : TForm ;
implementation
{$R *.DFM}
procedure TForm .FormCreate(Sender: TObject);
var
  i : integer;  // auto-initialized to zero
  MoreModes : bool;
  dm : TDeviceMode;
begin
  Memo .Lines.Clear;
  MoreModes := True;
  while MoreModes do begin
    MoreModes :=
      EnumDisplaySettings(nil,
                          i,
                          dm);
    Memo .Lines.Add('Mode ' +
      IntToStr(i) + ': ' +
      IntToStr(dm.dmBitsPerPel) + ' Bits Per Pixel ' +
      IntToStr(dm.dmPelsWidth) + ' x ' +
      IntToStr(dm.dmPelsHeight));
    Inc(i);
  end;
  NumModes := i;
  SpinEdit .MinValue := 0;
  SpinEdit .MaxValue := NumModes;
  GetMem(lpDmArray, sizeof(TDeviceMode) * NumModes);
  FillChar(lpDmArray^, sizeof(TDeviceMode) * NumModes, #0);
{$IFOPT R+}
  {$DEFINE CKRANGE}
  {$R-}
{$ENDIF}
  for i := 0 to (NumModes -  ) do
    EnumDisplaySettings(nil,
                        i,
                        lpDmArray[i]);
{$IFDEF CKRANGE}
  {$UNDEF CKRANGE}
  {$R+}
{$ENDIF}
end;
procedure TForm .Button Click(Sender: TObject);
var
  ReturnVal : LongInt;
begin
{$IFOPT R+}
  {$DEFINE CKRANGE}
  {$R-}
{$ENDIF}
  ReturnVal := ChangeDisplaySettings(lpDmArray[SpinEdit .Value],
                                     CDS_UPDATEREGISTRY);
{$IFDEF CKRANGE}
  {$UNDEF CKRANGE}
  {$R+}
{$ENDIF}
  with Memo .Lines do begin
    case ReturnVal of
      DISP_CHANGE_SUCCESSFUL: Add('DISP_CHANGE_SUCCESSFUL');
      DISP_CHANGE_RESTART   : Add('DISP_CHANGE_RESTART');
      DISP_CHANGE_BADFLAGS  : Add('DISP_CHANGE_BADFLAGS');
      DISP_CHANGE_FAILED    : Add('DISP_CHANGE_FAILED');
      DISP_CHANGE_BADMODE   : Add('DISP_CHANGE_BADMODE');
      DISP_CHANGE_NOTUPDATED: Add('DISP_CHANGE_NOTUPDATED');
    end;
  end;
end;
procedure TForm .FormDestroy(Sender: TObject);
begin
  FreeMem(lpDmArray, sizeof(TDeviceMode) * NumModes);
end;
end.