The 24-year-old, who is currently under contract at Blackpool but has not played a minute of football since November 2014, posted a statement to Twitter on Monday night asking for forgiveness.
He said: 'I just want to take the time out to write this post as I feel like I need to get this of (sic) my chest.. I have seen 2 of my good friends pass away in a short space of time... Whilst over coming this it has made me realise life really is to (sic) short and have really been taking things for granted.
'I would like to use this opportunity to thank, Southampton, Newcastle, Swindon and Blackpool for giving me the chance to experience the dream of being a professional footballer.
'To add to this I would like to apologise to every one at these clubs, including management, players, staff and fans. I should have given more and been a better role model.'
Ranger returned to Bloomfield Road last week after spending 10 months away, with manager Neil McDonald admitting he did not know the whereabouts of his striker.