When you ask a question you need to provide some basic information
-Forum quick start https://forums.adobe.com/docs/DOC-5601
Mac or Windows, and EXACTLY which version of the operating system?
Recent Mac AND Windows operating systems have been known to cause "odd" problems
Are you using a computer Administrator account with full read/write permission?
What is the exact error message that you see?
Exactly which version of the program do you have that is causing problems?
There is no application called "Adobe". Adobe is a company that makes many different products. What application are you using exactly? Also, what exactly do you mean by "book"? We don't know if you are using e.g. Adobe Acrobat and the PDF version of a book, or if you are using Adobe Digital Editions to read an eBook. Or, if you are using InDesign and are actually working on creating a book. We need a lot more information.