The last time nobody made it to the summit of Mount Everest was over 40 years ago. Due to a variety of factors not a single person was able to summit the highest peak on earth in 2015. To start there was a massive earthquake killing hundreds causing avalanches and broken paths. Then the mountain was closed to tourists wanting to reach the top. When it finally did re open permits to climb were limited, a Japanese man came close but also could not make it.
As a side note it has been increasingly more dangerous to summit Mount Everest. Each year there is more demand from people to climb it. Each year there have been more deaths. Although I can see how tempting it is to want to climb Mount Everest (as it is something I want to do) I will be sure to only go when I have well above the minimum training and experience recommended.