It appears your certificate has been revoked, which is to say that Let’s Encrypt has been instructed to let user agents like browsers know that the certificate is not to be trusted anymore. This is typically something only the owner of the private key or account key can do (usually the domain owner/site operator), though in exceptional cases, it might have been something Let’s Encrypt does (i.e. when a certificate is mis-issued or used fraudulently). That’s unlikely to be the case here.
If you didn’t do this yourself, and this is some kind of managed/shared hosting environment where the certificate was automatically obtained and installed for you, it’s possible that your hosting provider did this for some reason (perhaps a bug). In that case, you would have to contact them.
If you generated the certificates yourself (for example with certbot or any other ACME client), you can simply obtain a new certificate (the same way you got the first one) and start using it. crt.sh shows two more certificates for your domain, issued about two weeks ago. If you have not revoked these, it would be safe to start using them (the installation would work the same way as it did the first time you deployed a certificate; if you need help with that, please provide more details about your environment).
Note that you do not need to revoke your certificate when you request a new one (i.e. renew it), you can just let it expire.