Site down due to an SSL Certificate Expiring

I started getting site down errors emailed to me every couple of minutes starting on Wednesday evening. This is what’s being reported:

Our systems have detected that your site - (suppressed) - went down on Mar 20, 2019 8:41pm and is returning "Certificate has expired.."

I searched for this in the hosting forums and see this is a problem that others have encountered and that it also hobbled their sites. It looks like the support team had to intervene as nothing was posted for user fixes.

This is a site I migrated from DreamPress Managed WordPress hosting (Apache) where I was using the LetsEncrypt free SSL certificates. I’m not sure how that may be affecting the ability to renew it here but am looking for assistance.

(As an aside, neither of the 2 sites that I migrated a few months ago during the beta actually came across functioning. It was a mess that I tried to resolve multiple times and then walked away from while I was finishing cancer treatments. I really do want to bring other sites over from DreamHost but I’m incredibly reluctant since it’s absolutely hobbled the 2 I tried to migrate. Not sure if this has any impact on the current issue.)

Thanks for any help someone may be able to provide in resolving the expired certificate crippling the site.

Sue.