The former 'Coronation Street' star was supposed to be in the hotseat for ITV1's 'Who Wants To Be A Millionaire?' on Thursday night but was dropped shortly beforehand.
Earlier she appeared on ITV's 'Daybreak' in tears as she apologised for posting a picture of herself online in which she was holding a gun to her head. The image caused a furore when she posted the photo on Twitter following the mass shooting in Newtown, Connecticut.
Her "postponed" appearance meant her chosen charity missed out on the winnings she could have collected with partner Rosemary Shrager, with whom she appeared on 'I'm A Celebrity... Get Me Out Of Here!'.
Instead her place was taken by 'Made In Chelsea' star Hugo Taylor, who competed for another worthy cause.
Helen called her decision to post the picture on Twitter "the stupidest thing I have ever done in my life" and apologised to any of the victims' families who may have taken offence. She explained that she had placed it online because she had a hangover.
The image, in which she appeared in lingerie, was taken in a fashion shoot in October.
Explaining her withdrawal from 'Millionaire', a spokeswoman for ITV said: "ITV and Helen Flanagan have both agreed to postpone her appearance."
Rosemary and Hugo went on to win £20,000, but the programme's biggest winners were Des O'Connor and Lee Mack, who notched up £150,000.
JLS stars JB Gill and Oritse Williams won £50,000.