Wide receiver Antonio Brown has apologised to "the organisations I offended" as he bids to return to the NFL and "repair what I broke".
Brown is without a team after he was released by the New England Patriots earlier in the season amid allegations of sexual assault against him, which he strenuously denies, and misconduct.
The 31-year-old's departure from the Patriots in September was the latest move of a chaotic 12 months, with the player having also left the Pittsburgh Steelers and then the Oakland Raiders.
Brown clashed with quarterback Ben Roethlisberger before getting a trade away from the Steelers, joining the Raiders.
However, he never played for Oakland, ultimately calling for the team to release him - and getting his wish - after numerous controversies, including a holdout with the NFL and a fine from the Raiders.
A stint with the Patriots was cut short, too, but Brown hopes to make amends - despite previously saying he would not return to the league.
"First and foremost, I'd like to apologise to my family, friends and anyone who I offended," he wrote on Instagram on Friday.
"I never once meant to make anyone feel like I wasn't thankful and appreciative of the opportunity that I was afforded to play the game I love. I've worked hard over the years to earn a chance to compete in the greatest game on earth.
"Over the years I was met with challenges and I can honestly say I didn't handle those challenges in the manner that I should have.
"Over the past few weeks I've had the opportunity to think about everything that's transpired and I am deeply sorry to all who I've offended.
"While my behaviour was inexcusable, sometimes when people are coming at you with false information and allegations, we handle ourselves in ways that we sometimes regret.
"I do take full responsibility for my actions and I'm working everyday to repair what I broke.
"I do know that if I'm ever given the opportunity to play the game that I love, I'm going to work extremely hard to show the world how much I appreciate another chance.
"To the organisations that I offended, I offer my sincere apology to you and my hope is that you forgive me and help me move on from this minor setback. I look forward to competing and helping a team reach their goals."