Hi Danish,
It's a very interesting topic. Having a comprehensive knowledge of the given topic serves no purpose until attempted systematically. In spite of the fact that you will gather whole information on the topic using several sources not only a single recommended book.
As far as the questions on this topic are concerned, there may be questions on the comparison of the current and past condition of the Muslim Ummah, Ways to regain the past glory, Factors of the demise of Muslim Ummah, Solutions to the Current problem, Role of Intellectuals, Effective Leadership for The Muslim Ummah, and so and so forth.
All the best

Thanks