Karen barely survived Bullseye's attack, and was in a coma in the hospital. Daredevil was filled with rage and broke into the Kingpin's apartment at night, where he killed him in cold blood.
Matt turned himself in for murder, and was tried by jury. Doctor Strange and Captain America sat on the stand giving strong testimonies to Daredevil's character, but the jury still found him guilty and sentenced him to forty-four years in prison. In jail, Matt was mostly ignored by the rest of the population since he had killed the Kingpin. Foggy and Nick Fury from SHIELD visited him, giving him the news about Karen returning to her drug habit and disappearing. Foggy was disbarred.
Fifteen years later, Matt was released for good behavior, and did his best to move on with his life, never returning to the Daredevil persona. The worst thing that ever happened to Daredevil was watching his one true love Karen Page die in his arms after a brutal attack by his archenemy Bullseye. The events that followed spiraled Matt Murdock's life out of control and he has never recovered.