As we saw at Night of Champions 2015, Sting suffered a career ending neck injury at the hands of Seth Rollins when he took a Buckle Bomb.
Sting then went on to announce his retirement from Professional Wrestling at WWE Hall of Fame 2016 ceremony before WrestleMania 32.
It should should be noted that Sting still hasn’t got a neck surgery done. Sting has noted in interviews that if he gets the surgery done, it would mean his in-ring career would be over (which is him just working the fans as his in-ring career is indeed over after that injury whether he gets a surgery or not).
Dave Meltzer noted that Sting hasn’t the surgery done yet as it would affect his day-to-day life, but he will have to get it done at some point in his life.
It should be noted that Sting is still signed to a WWE Legends contract, which means WWE can ask him to appear at any event whenever they want.
Below is the move that ended Sting’s career: