Please fill out the fields below so we can help you better. Note: you must provide your domain name to get help. Domain names for issued certificates are all made public in Certificate Transparency logs (e.g. crt.sh | example.com), so withholding your domain name here does not increase secrecy, but only makes it harder for us to provide help.
The operating system my web server runs on is (include version): Debian testing
My hosting provider, if applicable, is:
I can login to a root shell on my machine (yes or no, or I don't know): yes
I'm using a control panel to manage my site (no, or provide the name and version of the control panel):
The version of my client is (e.g. output of certbot --version or certbot-auto --version if you're using Certbot): 2.1.0
The hard drive on my server died, and it turned out my backups had been failing quietly. So I have completely reinstalled the server and I want to reinstall letsencrypt. I have tried searching for instructions but I have found nothing that matches my situation.
TL;DR: You simply need to issue new certificates. You could do whatever you did when you obtained them in the past.
I'm not sure what situation you think you are in that none of the directions match yours, but you only neeed to issue a new certificate, which is one of the most common scenarios.
Your certbot could use an update to the current version, 2.9.0.
Have you attempted any methods outlined at the Certbot website?
If you have, which method are you using and what difficulty are you encountering?
The template you filled out already asked for that information, but you appear to have deleted the question pertaining to the commands you ran and their output. Those are important to know.
Yes, you said you had to completely reinstall your server because backups were lost.
So, you are starting over just like a new system.
When you request your first cert you will get new ACME Account. If you previously had special privileges on your ACME Account you will need to re-request those with the new account. These would be rate limit exemptions or ECDSA allow-list. If you never requested those then don't worry about them.