I was looking through all the certificates today & found many that looked dubious to me, from unknown companies in China, Taiwan, Turkey, etc. I 'deleted/distrusted' several of them, although they all seem to have since re-appeared (at least some have for sure). But now I find there are some websites I cannot connect to. I suspect I have deleted part of the trust chain between the website & firefox browser. Is there anything I can do to restore the required certificates?