By disappeared, I assume you mean disappeared from the spotlight. Some child actors who went onto careers outside of the acting business include:
Carrie Henn from Aliens
Bradley Pierce from Jumanji
Barret Oliver from The Neverending Story
Daniel Tay from Elf
Ross Malinger from Sleepless in Seattle
Ariana Richards from Jurassic Park
Jeff Cohen from The Goonies
Jonathan Lipnicki from Jerry MaGuire
Ross Bagley from Independence Day
Amy O'Neill from Honey, I Shrunk the Kids
Devin Ratray from Home Alone
Mara Wilson from Matilda
Jake Lloyd from Star Wars Episode 1: The Phantom Menace
Eight child actors who disappeared from film are Barret Oliver, Ariana Richards, Carrie Henn, Jeff Cohen, Mara Wilson, Devin Ratray, Anna Chlumsky, and Jonathan Lipnicki.
Nova - 1974 The Search for the Disappeared 14-1 was released on: USA: 14 October 1986
Disappeared - 2009 Innocence Lost 4-14 was released on: USA: 2 January 2012
Disappeared - 2009 Birds of Prey 6-14 was released on: USA: 11 February 2013
Disappeared - 2009 Footprints in the Sand 5-14 was released on: USA: 9 April 2012
Dennis Miller Live - 1994 Child Actors 7-2 was released on: USA: 14 January 2000
Yes. At 14 you are a child who is a teenager.
Disappeared - 2009 A Mother's Mission 3-11 was released on: USA: 14 March 2011
Disappeared - 2009 The Darkest Night 3-7 was released on: USA: 14 February 2011
Disappeared - 2009 Memory Lane 4-8 was released on: USA: 14 November 2011
it happened to me when I was a child. It was just one line on many of my teeth. They disappeared as mysteriously as they appeared.
The cast of Disappeared - 2008 includes: Louisa Lytton as Stacy Suzanne Serwatuk as Marsha Lisa Warner as Casy