//方法1
uses ShlObj;
SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST, nil, nil);
//方法2
procedure TForm1.Button1Click(Sender: TObject);
begin
SendMessage(FindWindow('Progman', 'Program Manager'), WM_COMMAND, $A065,0);
end;//方法3
procedure RefreshDesktop;
var c1: THandle;
begin
c1:=FindWindowEx(FindWindowEx(FindWindow('Progman','Program Manager'),0,'SHELLDLL_DefView',''),0,'SysListView32','');
PostMessage(c1,WM_KEYDOWN,VK_F5,0);
PostMessage(c1,WM_KEYUP,VK_F5,1 shl 31);
end;