恢复ActionBar样式或主题

Question

如果我在FragmentActivity中的片段中这样做：

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setHasOptionsMenu(true);
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    //inflate menu

    //change actionBar
    getSupportActionBar().setLogo(R.drawable.menu_icons_alerts);
    getSupportActionBar().setBackgroundDrawable(new ColorDrawable(Color.BLUE));
    super.onCreateOptionsMenu(menu, inflater);
}

如何恢复actionBar的默认样式/主题？

Thx in advanced！