Can I get back (undelete) books I deleted from KyBook 3?

Probably not. iPhones and iPads do not have a Trash can like Macs or Windows and Linux PCs, so there is nowhere to undelete from.

This means that once deleted from the device, books are irrecoverable, which is why KyBook 3 always asks you to confirm before deleting books.

It is possible that the book files could be restored if they were in cloud storage rather than on the device itself. Please check with your cloud storage provider.