A baby girl who spent her life in and out of intensive care has died just days after her parents begged for help to find a lost mobile phone that held all their memories of her.

Dee and Jay Windross on Saturday launched a public appeal to find the Samsung mobile after it was picked up from the toilets near Target at Chadstone Shopping Centre over the Easter long weekend.

The little girl has battled an undiagnosed neurological condition since she was born. Credit:Jay Windross/ Facebook

The parents this week revealed Amiyah had died after battling an undiagnosed neurological condition from the day she was born 11 months ago.

"It is with utter sadness that Dee and I inform everyone that Amiyah Victoria grew her wings at 2.05am on Wednesday morning," Mr Windross wrote on Facebook on Thursday.