Since Sarah Jarosz's site is now hosted through Squarespace, there was no need to renew her hosting with Hostrocket... and I felt pretty confident about that until her site stopped working the next day. Hostrocket is also not listed with a provider-specific guide on Squarespace support, so I thought I'd made a huge mistake.
If this has happened to you - I'm here to tell you that it's an easy fix, but you can't do it on your own. For some reason Hostrocket keeps the advanced DNS settings locked until you call support and ask for access.
Step 1: Calm down! Your site will be back up and running in just a few minutes!
Step 2: Call 1.866.519.7079 and tell them you need access to the advanced DNS settings for your domain. They'll confirm your identity, set up a login with you, and it's as simple as that. (Some providers can take up to 72 hours to recognize DNS changes, but Hostrocket was immediate once I had access!)
Step 3: Follow Squarespace DNS Settings and enter C & A Name Records into Hostrocket
Step 4: Save Hostrocket settings, refresh Squarespace, and there you go!
This tweet was right after Sarah's site came back... sigh of relief!
RT when yours is back up and running so I know this post helped :-)