Thank you for your reply. Yes, I am in control of the domain name, the log-in and password to my domain registrar.
I am in contact with my hosting company and you are right, I do not have the username and password to administer my account on the hosting company's servers. This because it apparently doesn't matter to them who the rightful owner is, or who controls the domain name, it matters only who initially set up the hosting and who has got the username and password. And my ex-contractor has set this up and he left without handing over username and password to me (welcome to Thailand).
What my hosting company let me do is paying the bills, so the site won't be shut down for the time being.
I did nowhere see technical questions about my hosting when I initially asked for help. Or do you mean selecting the right category with the title server (drop down menu?). Unfortunately, the entire process of was done by my ex-contractor and we never discussed much about technical issues. What I know is...
I can send and receive emails via the server and I have access to the control panel to check my emails. I do not have the "master" account, to add new emails (which kind of sucks).
In regards to the extension of the SSL certificate, when I asked my hosting company, first they said they didn't know anything about it but after doing further research and I found out that they advertise Let's encrypt certificate on their website, and after confirmation from your end that my SSL certificate is from Let's encrypt, I was asking a second time, and their reply was:
"Sehr geehrter Herr Graf
Ja das Let's Encrypt ist ein kostenloses SSL Zertifikat der sich alle drei Monate automatisch verlängert. Daher wird hierfür keine Rechnung erstellt und Sie müssen nichts unternehmen.
Freundliche Grüsse. Emre Ciftci"
English translation: Dear Mr. Graf, Yes, the let's encrypt is a free SSL certificate which extends automatically every three months. That's why we do not invoice you for this and you don't have to do anything else. Kind regards. Emre Cifci.
Does this mean we can trust the the hosting company and stop worry about it and touch wood everything is going to be fine?
Look forward to hearing from you and thank you so much for your help.