It means that something or someoen has removed Adobe's root certificates from your trust list, either gloobalyl in your operating system or just in the browser. Anyway, you did not provide any system info, so this is not going anywhere. We need to know operating system, browser used and all that and even then it's possible we can't do anything about it, because some security tool or your IT department has imposed this...
In addition to answering the questions that Mylenium has asked, can you post a screenshot of the message you are seeing?
[topic moved to Flash Player forum]
so how do i get the certificate back. Why would this happen
Nobody can tell you anything as long as you refuse to answer our questions.