I'm located in Syria and I'm writing a motivation letter to be used in applications for master of computer science scholarships. Would it be useful to mention how I managed to succeed with my studies despite all the awful things that happened in my country and my city ?
Yes, you should mention these issues. Your situation is unusual, and it's helpful if the application puts everything in context for the admissions committee. I don't know whether it will help your chances of admission, but if there are deficiencies in your application it might explain why you could not fix them, and in any case it certainly won't hurt your chances.