Dear [Support Team/Technical Support],I hope this email finds you well. I am writing to seek urgent assistance regarding an issue I am experiencing with the BOOK app.Recently, I encountered a problem while attempting to open a PDF document within the BOOK app. This PDF contains vital materials related to my entrance exams, and it is imperative that I access its contents promptly. However, despite being able to open the PDF previously and having marked and underlined important sections within the app, I am now unable to open it.I have tried several troubleshooting steps on my own, including restarting the app and my device, checking for updates, and ensuring PDF compatibility. Unfortunately, none of these efforts have resolved the issue.Given the importance of the PDF contents to my academic pursuits, I would greatly appreciate any assistance you can provide in resolving this matter promptly. If there are specific troubleshooting steps or updates that I may have overlooked, please advise accordingly.Additionally, if there are any known issues with the latest version of the app or if other users have reported similar problems, I would appreciate any insights you can share.Please let me know how best to proceed in resolving this issue. Your prompt attention to this matter is highly valued, as I am eager to regain access to my study materials as soon as possible.Thank you for your assistance and understanding. I look forward to your prompt response.