function CountFiles(const ADirectory: String): Integer;
var
 Rec : TSearchRec;
 sts : Integer ;
begin
 Result := 0;
 sts := FindFirst(ADirectory + '\*.*', faAnyFile, Rec);

 if sts = 0 then
 begin
 repeat
 if ((Rec.Attr and faDirectory) <> faDirectory) then
 Inc(Result)
 else if (Rec.Name <> '.') and (Rec.Name <> '..') then
 Result := Result + CountFiles(ADirectory + '\'+ Rec.Name);
 until FindNext(Rec) <> 0;

 SysUtils.FindClose(Rec);
 end;
end;

procedure TForm1.Button1Click(Sender: TObject);
 var f:string;
begin
 f:=inttostr(CountFiles('C:\Windows'));
 Showmessage(f);
end;