@info881540f9437 - How did you setup your domain? Is the DNS for the domain pointing or directing requests to the Droplet IP or DigitalOcean’s Nameservers? If so, and the request was semi-recent, it’s possible that the DNS changes have yet to fully resolve. You can use a tool, such as the one below, to see if the domain is resolving elsewhere. This will give you an idea of the status of resolution.
As for the Droplet itself, you’re using Ubuntu - what all has been installed? - Specifically, what web server. What changes did you make the the web servers configuration file?
In regards to accessing the droplet, is there an active Firewall? If so, did you white-list your IP prior to logging out, restarting the firewall / droplet or making changes to the firewall (i.e. adding new rules)? If any of these things happened and your IP wasn’t white-listed, there’s a good change you were temporarily blocked. In such a case, you should be able to access the console from within the DO control panel.
If that too fails, you should be able to do a password reset by powering down the droplet and requesting a reset through the Control Panel.