How can one overcome the negative feeling of failing the الثانوية (High School Certificate) and move past losing a school year?

One must be patient with Allah's decree and destiny, for everything Allah decrees for the believer is good for him, as attested by the Prophet, peace and blessings be upon him: "Wondrous is the affair of the believer, for there is good in every matter of his..." Failure is not a measure of a wasted life; rather, true waste is spending one's life in disobedience to Allah. Sadness is not among the stations of faith, and Allah Almighty has not commanded it; rather, He has forbidden it, for it weakens the heart and hinders willpower. And whoever knows Allah and loves Him, his sorrows will be dispelled.