Unable to access by domain name after web site deployment

I am writing to ask you a question because my site (and domain purchase) that I deployed using EC2 of AWS from Ruby(ruby on rails) is no longer displayed!

The EC site was deployed as above, but it was displayed after I accessed it properly for a while after it was completed and deployed, but after leaving it for a while, it was no longer displayed.

When accessed now

Cannot access this site
Could not find server IP address for www.(site name).work.
(Site name) Google work
ERR_NAME_NOT_RESOLVED

appears, and when I entered the Elastic IP of the EC2 instance and accessed it, the blue and white screen of nginx, Welcome to nginx on the Amazon Linux AMI! was displayed.

It took about a month for me to leave it alone, and the only thing that changed during that time was that I restarted it with PC (mac) updates and I haven't used the terminal since I restarted it.

Here's an article I used to refer to during deployment↓
For beginners: How to deploy Rails web apps to AWS (EC2) - Qiita

That's all, but what should I do to display this site again?

If you come up with any countermeasures, please take care of me m(._.)m

I entered EC2 by connecting to ssh at the terminal, so the results I entered are as follows.

 [test_user@ip-10-0-1-174~]$ nslookup www. (site name).work

Server: 10.0.0.2
Address: 10.0.0.2#53

** server can't find www.work:NXDOMAIN