Answer by taking a quote from the following article:

Kevin Maurice Garnett (born May 19, 1976) is an American former professional basketball player who played for 21 seasons in the National Basketball Association (NBA). He played the power forward and center positions. In high school, Garnett was a 1995 McDonald's All-American at Farragut Career Academy and won a national player of the year award. He entered the 1995 NBA draft, where he was selected with the fifth overall pick by the Minnesota Timberwolves and became the first NBA player drafted directly out of high school in 20 years.

On February 19, 2015, Garnett agreed to waive his no-trade clause in order to be traded back to Minnesota in exchange for Thaddeus Young. Six days later, he made his return for the Timberwolves against the Washington Wizards at the Target Center, recording five points on 2-of-7 shooting with eight rebounds and two blocks in 19 minutes in his first game for Minnesota since 2007. He appeared in just five games for the Timberwolves in 2014-15, before sitting out the team's final 21 games of the season due to a nagging knee injury.  On July 11, 2015, Garnett re-signed with the Timberwolves to a two-year deal. On November 15, 2015, Garnett became the fifth player in NBA history to play at least 50,000 minutes. He joined Kareem Abdul-Jabbar, Karl Malone, Jason Kidd and Elvin Hayes. Garnett played a season-high 23:54 against the Memphis Grizzlies, recording eight points, five rebounds and four assists. On November 23, he had a season-best game with 8 points and 10 rebounds in a 100-95 win over the Philadelphia 76ers. On December 1, he recorded four points and eight rebounds in 20 minutes against the Orlando Magic, surpassing Jason Kidd (50,110) for third on the NBA's career minutes list. Four days later, in a loss to the Portland Trail Blazers, he became the 15th player in NBA history to surpass 26,000 career points.  On December 11, 2015, Garnett passed Karl Malone as the NBA's all-time leader in defensive rebounds during Minnesota's 111-108 overtime loss to the Denver Nuggets. He finished the game with four defensive boards to give him 11,409 for his career, three ahead of Malone. Garnett appeared in 38 of the team's first 45 games of the season before missing the entire second half of the season with a right knee injury, the same knee that kept him out of 25 games in 2008-09 when he was playing for Boston, as well as much of his post-trade time in Minnesota during the 2014-15 season.  On September 23, 2016, Garnett announced his retirement after 21 seasons in the NBA. While Garnett did express interest in playing for one more season with the Timberwolves, primarily with the goal in helping the team make it to the playoffs again with its promising young players and new head coach, he also told the team's owner that he wasn't sure that his knees would hold up for one more season.

When did Kevin Garnett return to Minnesota?
On February 19, 2015, Garnett agreed to waive his no-trade clause in order to be traded back to Minnesota in exchange for Thaddeus Young.