Everyone has a different idea as to what night Laylatul Qadr is on. Some say it's the 27th, others say differently... But how do we know when it is exactly? Will it forever remain a mystery?
All we know for sure is that Laylatul Qadr falls on an odd night. That means we have 5 nights to try our best to witness it...
Shaykh Yasir Qadhi explains and answers the question
Laylatul-Qadr is one of the mysteries that our Prophet (sallallahu alaihi wa salam) has told us Allah intentionally has kept a mystery. He did not tell us the exact night, but we know that the strongest candidates are the odd nights of Ramadan. We all know this: 21, 23, 25, 27, 29. So, five nights we have to be extra, extra observant. And of those five, 23 and 27 have the strongest possibility. And of those two, 27th has the strongest possibility. And one opinion is that Allah changes Laylatul-Qadr every year, and it varies from year to year. And so one year it might be 21, one year it might be 23. So, give it your best, it's only five nights of the year and of them, the odd nights of the last 10 nights. Do what you can at Allah (subhanaha wa ta’aala) will bless you (inshaAllah wa ta’aala).