Andrew Gosden was 14-years-old when he was last seen on CCTV getting off a train at London Kings Cross in September 2007, hours after he withdrew £200 and bought a one-way ticket.
South Yorkshire Police has been searching for him since the last sighting and the force made another plea for information today and released age-progression photographs, which show what he may look like at the age of 28.
Detectives say he has a “distinctive right ear” and was also deaf in his left ear and wore glasses because he had poor eyesight.
Detective Inspector Andy Knowles said: “My main aim is to encourage anyone who might know Andrew to contact police.
“By providing details about his appearance we are hoping to spark a conversation between friends or people that might know him as the 28-year-old man he is today.
“Does someone you know have gaps in their life history? Do you know someone with this distinctive double ridge on his right ear? Is there someone in your life, your street, or your community that might be Andrew?”
He added: “Time does not lessen the pain for Andrew’s family. I know from speaking to them that with every passing day, month, and year their desire to know what happened to him grows.
“If you have any answers to these questions, perhaps today is the time to speak to someone.”
Kevin Gosden has told the Yorkshire Post that he has endured “ endless torture” while trying to find out what happened to his son.
Mr Gosden said his son seemed like “his usual, normal self” the night before he disappeared and on the morning of September 14 in 2007 he left in his school uniform and said “see you later”.
Speaking on the 12th anniversary of the disappearance, he said: “We just want to know what the hell has happened to him. It is just unanswerable and an endless torture for us.
“Your head doesn't know if you are grieving or not, it is the worst part of mental torture in existence - it's just the not knowing."