When I had interviews or applied for jobs, my rule was that if I didn't hear back in two weeks, I followed up once, and if I didn't hear from them after that, I moved on.
If they had every intention of interviewing you and had other issues (interview for other person ran longer, forgotten the time, miscommunication), they would have called back and said, "...
Have you tried contacting the main line of the company and see if you can track her down? She may have had a major family crisis and had to step out for a few days. Even if you don't reach her, you may get someone close to her who could fill in the details, or has picked up her duties.
If you do reach her, I hope there is a really good reason for ...
Not necessarily ghosted. It's possible that the person was dragged into something else. Give it some time (say 3 days) and see if you get a response back.
If not then just move on.
The number of times that haven't got the interview call, due to agent to HR to interviewer miss communication.