To solve the majority of the problems that may arise:
1. Make sure you're in the range of a good Internet connection.
2. If something is wrong with one particular book, delete it from your library.
3. Reinstall the app.
4. Open the app and make sure you've logged into your account, i.e. used the same login method, e.g. Facebook.
5. Search for and add the book you've deleted to your library.
6. Wait till all the books are synchronised.
7. If you have a subscription issue, select "Restore subscription" in the app settings.
If it doesn't help, email us and specify your login.