Two heartbroken parents have made a desperate plea for the return of a missing phone full of photos of their terminally ill daughter.

Dee Windross accidentally left her smartphone alone in a toilet cubicle while she washed her hands at Melbourne's Chadstone Shopping Centre on Saturday afternoon.

Within seconds it was gone, and with it, hundreds of photos of her daughter Amiyah.

The photos are all the more special, her husband Jay told 7NEWS.com.au, because Amiyah only has days to live.

"In the past, we'd be worried about our social life and all that," he said.

Jay and Amiyah Windross Credit: Facebook

"That wasn't even close to the first thought."

Chevron Right Icon 'This is worth life to us'.

Jay said the phone had a sentimental value and has pleaded with whoever found it to come forward in an emotional Facebook post.

"We understand that you have either found a new phone to use, or you can sell it to make money, but please understand that this means more than money to us.

"This is worth life to us.

"If it's money you need, we will gladly offer you a cash reward for the return of the phone. No questions asked. No grudge held."

Amiyah

Infant Amiyah has spent much of her young life in hospital.

"Ever since birth, we could tell there was something up," Jay said.

Amiyah is an undiagnosed baby, meaning doctors were unable to find a diagnosis for her multitude of conditions.

Jay says she's spent almost 200 days of her 11-month life in hospital and was recently taken into intensive care.

Community support

Jay's emotional Facebook post has already been shared more than 83,000 times in 17 hours.

"With just how sentimental it is, we thought we'd try the power of social media.

"We can only hope that the message gets to the right person."

Many have suggested he check for a digital back-up of the phone.

But Jay says he and his partner aren't technologically savvy enough.

Chevron Right Icon 'We beg you as grieving parents not to wipe the phone.'

He says his greatest fear is that the photos will be lost forever.

"We beg you as grieving parents not to wipe the phone," he wrote.

"We'll do whatever we need to do to get those memories back."

The parents have urged anyone who comes across the phone to contact them or hand it in to the Monash Children's Hospital.