Notability File Recovery Specialist

We need help recovering a frozen Notability file after textbook pages stopped displaying on our iPad. The original PDF pages are missing, but typed notes, highlights, and inserted pages remain visible. We have the original textbook PDF, the affected .note file, and a PDF export of annotations and inserted pages. We want a repaired .note file that restores textbook pages and keeps annotations editable, or a combined PDF where highlights and notes align correctly with the textbook and inserted pages. Please describe your approach and quote a small test covering one textbook page, one inserted note page, and the next textbook page before handling the full document.