If your address shows a page that says Website Expired, Squarespace has stopped serving your site. Your content is almost certainly still there. The billing lapsed.
Squarespace shows this page when the site subscription ends, a card payment fails, or a trial runs out. Visitors see it instead of your site. Search engines see it too, and a long outage can push your pages down in results.
Use the password reset. If the account belonged to a former staff member or a web designer, contact Squarespace support with proof you own the business. Do it soon. Squarespace keeps expired sites for a limited time before removing them.
Want the rest of your site checked after it is back? Run a free 40-point check at tinkeraudit.com.