Thannks for the answe.
Let me udpet you.
I've already tried several (2-3 reboots) with no success. And as I told on the post, via computer I could see that there was NONE ebook on documents fodler.
What result was a long press reboot, 30 seconds holding the reset button. I found this solution googling and thought "let me try this", not knowing what would do
What does it do this 30s long press button holding exactly?
What about a better method for keep track of my read and unread books, can you help?