Rabia Ahmad, 15, disappeared from her family's Beverly Hills home on December 31, taking only a small number of possessions with her.

"She is safe and well, but tired because she didn't want to fall asleep on the trains," Rabia's older brother, Nasir Ahmad, 22, said.

"She just needed to get out of the house."

Mr Ahmad made a list of all the possible places the teenager might have gone, and organised a search team on Friday night that brought family members and people from the local community together.

A Facebook page titled, "Help Find Rabia Ahmad" was also set up over the weekend and was flooded with hundreds of comments and attracted over 4000 page likes.

One person, not connected with the family, told Fairfax Media the Facebook page "really helped with the search".

The page has since been closed.

On Sunday, the teenager was finally tracked down by two of her aunts in Strathfield, after police received a tip-off and the family distributed pamphlets with Rabia's photo around the station.

She had not made contact with friends and had simply "gone back and forth" on the train, Mr Ahmad said.

He said he will give Rabia a few days to recover before asking her exactly why she ran away.

"I'm the older brother so if it is about my parents, then I'm going to fix it.

"I told her, if you wanted to go out of the house, I could have taken you. I could have dropped her at a friend's place or we could have gone away for a few days."

Now that Rabia has returned, Mr Ahmad said his family could celebrate the start of 2014.

"Because she's back, the Ahmad family's new year starts today."