It's not "our" product. It's Atlassian's *Service*. They also provide this "Answers" site for the community of their users to talk and help each other out. Your link goes to a Cloud JIRA installation that Atlassian hosts, but it's actually *your* system. If you cannot log into it, and can't use the "reset password" options for some reason, then you need to contact your administrators. If you are an administrator, and you can't get in because the site is down, then raise a support request with Atlassian Cloud support (note that the "site down" pages all have a button to take you straight there)
When I try access this link: https://letech.atlassian.net/
We can see that shows a error and there is a Resolve issue button... have you seen this?
My thoughts are that your cloud server can be facing some internal issue and if this is the case you might open an issue to cloud support team..
Another point that might be causing your issue is some bill payment issue...
Either way, opening an issue to cloud support is the best option for identify the your root cause issue
As you state the message has been there for 2 days you should mention that when you raise your support request. This may then help you get a higher priority resolution. It is worth reviewing the page https://www.atlassian.com/cloud/security/ that tells you more about the service you have purchased.