Recreate ssl certificates after domain name change

Hi guys.

I ended having to change my dynamic dns (provided by the dynudns service) after it seemed my system was being remotely access by someone I don’t know, also changed my IP address and user passwords.

I can still locally access the system, but getting invalid certificate remotely now.

how do I re-generate my ssl certificates, I tried uninstalling and reinstalling nginx ssl proxy and the dynudns add on.