Missing Sydney teen 'sleeps with a teddy'

A teenager who was last spotted climbing into a car outside her Sydney home two days ago is "just a baby" whose family is desperate to find her safe, her father says.

Police say 14-year-old Krystal Muhieddine was seen getting into an unknown silver sedan, which bore P-plates, outside her home in leafy Hunters Hill at 5.30am (AEDT) on Tuesday.

On Thursday her parents Wally and Suzanne pleaded for their daughter to make contact.

"We can sort this out. Just come home," Mrs Muhieddine told reporters.

She said Krystal - the second-youngest of four girls - had sneaked out to see a movie on Friday, telling a big sister she had her mother's permission before lying to Mrs Muhieddine, claiming a friend's mother was planning to collect her.

A tearful Mrs Muhieddine told reporters she had given Krystal a talking-to - "just normal parent stuff" - but that everything at home was otherwise well.

"She's never done this before," she said.

The high-schooler's friends say she has recently spoken about a boy, and her parents say she might have been communicating with someone online before she disappeared.

But her father says she's never had a boyfriend.

"She's sweet, she's innocent, she's young," he told reporters.

"She's not street-wise - she's actually quite bright and sophisticated in so many other ways but, you know, she sleeps with a teddy bear.

"She took her teddy bear with her."

He said it was the first time she had been anywhere on her own and he and his wife were losing sleep.

"If you're with Krystal, you need to understand she is a baby, she is not an adult, she's tall but she is actually a baby. You need to call us and bring her home safely," he said.

Ryde Local Area Command Detective Inspector Richard Puffett said investigators were scouring social media as well as trying to track down the sedan in which Krystal was last seen.

It is believed she left with a green bag containing clothes and had a small amount of cash.