ONE (1) singular epub wiped off my phone

I'm genuinely so upset. These past few weeks I've been reading this really long webnovel -- 500+ chapters and nearly 1.5 million words -- and i've been so invested i had about 980 ish highlights/notes on it. However, today i noticed my phone storage getting a little too full, so i delete a few videos and i get back to reading, but a few minutes after i notice my phone battery being too low so i charge it. The next hour, i open my phone to read more only to find out that the epub i was reading is just. gone. It's not in my ibooks app, it's not even in my files, no matter where i look.

I thought this was like the past few instances where they delete your books if your storage is too full but every other epub i have is still in both my ibooks app and in my files. And i have no memory of even deleting anything in my files before i charged my phone

Does anyone know how to fix this? I genuinely don't want to go back and rehighlight everything again. I've tried redownloading the epub but my progress is still gone, i'm honestly stumped...