What should I do about the intense sadness that has afflicted me due to my failure to observe Qadr Night, which was said to be the twenty-seventh night of Ramadan, and is there a wisdom behind my not observing that specific night?

The reward for observing Laylat al-Qadr is immense, and it brings forgiveness for past sins. It occurs on the odd nights of the last ten days of Ramadan, and it cannot be definitively stated that it is the 27th night. Observing it can be achieved by spending a portion of the night in worship or through various acts of obedience, such as recitation (of the Quran), prayer, remembrance (dhikr), and studying Islamic knowledge. Missing an act of worship may motivate a Muslim to strive harder in the future, or it could be due to a sin that constrained the servant.