In the 2012 National League Division Series, the San Francisco Giants dropped their first two games against the Cincinnati Reds, but roared back with three consecutive wins to advance to the League Championship Series.
There were no teams ever came back from 3-0 deficit. There were some who forced a game 7 though. However, there were 7 teams to win a playoff series from 3-1 deficit.
That has happened twice. In 1942, the Toronto Maple Leafs came back from a 3-0 deficit to defeat the Detroit Red Wings 4 games to 3 and win the Stanley Cup. In 1975, the New York Islanders came back from a 3-0 deficit to defeat the Pittsburgh Penguins 4 games to 3 in a second round playoff series. The Islanders were defeated in the next round by the Philadelphia Flyers.
Montreal Canadiens came back from a 3-1 deficit in 2010
The Pittsburgh Pirates came back from a 3-to-1 deficit to beat the Baltimore Orioles in seven games.
One memorable instance of an NHL reverse sweep in playoff history occurred in 2010 when the Philadelphia Flyers came back from a 3-0 series deficit to defeat the Boston Bruins in the Eastern Conference Semifinals. Another notable reverse sweep took place in 2014 when the Los Angeles Kings overcame a 3-0 series deficit to beat the San Jose Sharks in the Western Conference First Round. These instances are rare and showcase the resilience and determination of the teams involved.
The New York Yankees, who came back from a 3 games to 1 deficit against the Milwaukee Braves.
The Boston Red Sox baseball team came back from 3-0 to defeat the New York Yankees in the AL Championship series in 2004, 4 games to 3. The 1974-75 New York Islanders came back from a 3-0 deficit against the Pittsburgh Penguins to win the series, and almost did it again against the Philadelphia Flyers, tying that series 3-3, but losing game 7. The 1941-42 Toronto Maple Leafs actually came back from down 3-0 in the Stanley Cup Finals against Detroit, coming back to win the Stanley Cup. And of course the 2009-10 Flyers against the Boston Bruins.
Prior to the 2010 ALCS, once ... they were down 3-1 to the Milwaukee Braves in the 1958 World Series and came back to win.
The Yankees have never lost a seven-game World Series after leading 3 to 1. The 1958 Yanks, however, came back from a 3 to 1 deficit to beat the Milwaukee Braves for the world championship.
The Boston Red Sox baseball team came back from 3-0 to defeat the New York Yankees in the AL Championship series in 2004, 4 games to 3. The 1974-75 New York Islanders came back from a 3-0 deficit against the Pittsburgh Penguins to win the series, and almost did it again against the Philadelphia Flyers, tying that series 3-3, but losing game 7. The 1941-42 Toronto Maple Leafs actually came back from down 3-0 in the Stanley Cup Finals against Detroit, coming back to win the Stanley Cup. And of course the 2009-10 Flyers against the Boston Bruins.
The Toronto Maple Leafs came back and beat the Detroit Red Wings in the 1942 Stanley Cup final. The New York Islanders, in only their third NHL season, came back against the Pittsburgh Penguins in the quarter-finals in 1975. And in 2010, the Philadelphia Flyers came back from 3-0 in the series as well as 3-0 in Game 7 to take the Eastern Conference semifinal against the Boston Bruins
Detroit came back from a 3-1 deficit to advance over Orlando in 2003. The Magic won the first game, the Pistons won the second, Orlando won games 3 and 4 while Detroit won games 5, 6, and 7. Phoenix Suns came back from a 3-1 deficit to defeat Los Angeles Lakers in the first round of the Western Conference playoffs in 2006.