How to fix your connection is not private Attackers might be trying to steal your information

Recently I got this message when I try to visit my site

" Your connection is not private Attackers might be trying to steal your information from fun9ja.com (for example, passwords, messages, or credit cards). Learn more NET::ERR_CERT_DATE_INVALID" This server could not prove that it is fun9ja.com; its security certificate expired 7 days ago. This may be caused by a misconfiguration or an attacker intercepting your connection. Your computer's clock is currently set to Saturday, August 10, 2019. Does that look right? If not, you should correct your system's clock and then refresh this page.
Proceed to fun9ja.com (unsafe) 

I suspect this issue to be related to SSL Certificate.

The site is hosted on Vultr I installed WordPress using forge I also encrypt the site using forge let's encrypt

I don't have access to forge any longer as my subscription to the service has elapsed.

If it's an issue with SSL, please how do I renew my SSL Certificate without having to go back to forge, how do I do it manually?

Here is the site address: https://toptechboss.com/

Thanks for your help