Two years ago, Sandrine Jourdan walked up a friend's Sunshine Coast driveway and simply disappeared.

The Caboolture woman has not accessed her bank accounts, used her phone or wished any of her three children a happy birthday since then.

Missing woman Sandrine Jourdan has not been seen for two years. Photo: Supplied

She vanished – and her family just wants to know what happened to her.

For Sandrine's sister Christine Day it has been two long years of waiting, wishing and hoping with not a single clue as to her fate.

"I honestly don't know, as far as I know, she's dead, there is no way she would not contact us," Ms Day said.