Your domain is registered somewhere else and Squarespace cannot see the right records yet. Squarespace shows the domain as "Pending" or lists records with a red mark. One missing or wrong record is usually the whole problem.
a1b2c3d4), value is verify.squarespace.com. Some registrars add your domain to the end of the host by themselves. Type only the code.www, CNAME, value ext-cust.squarespace.com. Delete any other www record first. Two records on one name break it.@, values 198.185.159.144, 198.185.159.145, 198.49.23.144, 198.49.23.145. Delete old A records pointing at a previous host or a "parked" page.Run dig +short yourdomain.com and dig +short www.yourdomain.com. The first should list the four Squarespace addresses. The second should show ext-cust.squarespace.com.
Want the rest of your site checked after it is back? Run a free 40-point check at tinkeraudit.com.