Feeling blue because it just feels so hard? or dejected because you failed that exam you were to hoping to excel in?
Ask Allah for help and keep going. He understands. And as long as you're alive, there is hope :)
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
A strong believer is better and is more lovable to Allah than a weak believer, and there is good in everyone, (but) cherish that which gives you benefit (in the Hereafter) and seek help from Allah and do not lose heart, and if anything (in the form of trouble) comes to you, don't say: If I had not done that, it would not have happened so and so, but say: Allah did that what He had ordained to do and your" if" opens the (gate) for the Satan. ( Sahih Muslim 2664)
عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " الْمُؤْمِنُ الْقَوِيُّ خَيْرٌ وَأَحَبُّ إِلَى اللَّهِ مِنَ الْمُؤْمِنِ الضَّعِيفِ وَفِي كُلٍّ خَيْرٌ احْرِصْ عَلَى مَا يَنْفَعُكَ وَ اسْتَعِنْ بِاللَّهِ وَلاَ تَعْجزْ وَإِنْ أَصَابَكَ شَىْءٌ فَلاَ تَقُلْ لَوْ أَنِّي فَعَلْتُ كَانَ كَذَا وَكَذَا . وَلَكِنْ قُلْ قَدَرُ اللَّهِ وَمَا شَاءَ فَعَلَ فَإِنَّ لَوْ تَفْتَحُ عَمَلَ الشَّيْطَانِ " .