Hi Yusuf. Sorry to hear that you failed the exam on your first try. Below are a few tips that might help you as you continue your journey to obtain the PMI-ACP.
-As you've already seen by taking the exam, the content is almost all situational and options to questions almost always include answers that are very similar, which makes the test very difficult. In those cases, referring back to Agile mindset and principles will help answer these questions.
-Memorizing concepts may help a fraction in some cases (e.g. differences between Scrum, Lean, and XP), but embodying Agile principles and values will help the most (e.g. Agile Mindset). Remember, this is a psychometric analysis monitored test, which makes it very difficult.
-Know that 20 questions on the exam are pre-test questions that don't count. You'll know these questions when you see them because they'll usually ask you about a topic that hasn't been covered in Mike Griffiths' book or the Agile Prepcast. In other words, they come "out of left field." When you come across them, I wouldn't spend too much time on them. Just mark them for review and go back to them later.
-The Prepcast Exam Simulator is a wonderful tool to use for exam preparation. I used it personally to prepare for the exam. It very closely emulates the questions that will appear in the exam. As a matter of fact, several of them were almost exactly the same! After having read Mike Griffiths book once or twice, focusing on embodying the Agile Mindset, take the first Exam Simulator test. Don't be discouraged if you score below 70% because the Simulator is SUPER HARD. After having reviewed the questions you incorrectly answered within the Exam Simulator (the Simulator allows you to review every question, response, and why you got them wrong), I suggest reviewing those topics in Mike Griffiths' PMI-ACP Exam prep book, and you may want to read the book from cover to cover to really ingrain the topics in your mind. Again, it's all about the Agile Mindset. I would repeat the above process until you score a 75% or better on the Exam Simulator. One you get to that point, you'll have a really good chance of passing the exam.
Hope that helps.