restore default configuration

Please read this whole message before doing anything.

Back up all data.

Quit iBooks if it's running. Test after taking each of the following steps that you haven't already taken. Stop when the problem is resolved. Quit iBooks again before going on to the next step.

Step 1

Hold down the option key and select Go ▹ Library from the Finder menu bar. From the Library folder, move the following item, if it exists, to the Trash:

Cookies/com.apple.ibooks.cookies

Step 2

Delete this item in the same way:

Preferences/com.apple.ibooks.plist

Step 3

Delete this item:

Containers/com.apple.iBooksX

and move this one to the Desktop:

Containers/com.apple.BKAgentService

Restart the computer. To log out and log back in is not enough—you must restart.

When you launch iBooks, you'll be prompted to reset the library. Confirm. The library will be empty. Rebuild it by downloading your purchases from the iBooks Store and importing any other content you added. You may find the added content in the folder named "com.apple.BKAgentService" that you moved to the Desktop.