I replaced your domain name and platform id because this is a public forum and it's required to avoid sharing private information about your project. Please next time keep in mind that.
I am part of the support team, but for your case it's better to create a support case because we need to get more information to troubleshoot the issue.
We need to know which product are you using exactly, please check this official documentation. Or you are just using your self-hosted Wordpress on a Virtual Machine?
You can find a similar issue in the following Google Groups forum.
I suspect that having your webserver unmanaged for a few months can lead to a memory related issue. So best thing you could do is to ssh into the machine, check database logs (/var/log/mysql/) and check database service status
$ sudo systemctl status mysqld.service.