The Step On singer was backstage sharing a drink with the Fun Lovin' Criminals at their show in Manchester, England, when her Apple iPhone 6 disappeared on Friday (26Feb16).
"My iPhone was on my lap, next to my bag," she tells Britain's Manchester Evening News. "Some people came over wanting photos of me and some of the band.
"When I looked down I realised that my phone was missing. I looked around and asked if anyone had seen it, but nobody had."
Some of the music and photographs stored on the device had been saved elsewhere, but when Rowetta returned home she found her Apple computer's memory had been wiped.
As a result, she will now have to re-record vocals for a musical project with The Jam icon Paul Weller, according to the newspaper.
"I asked all my friends if they had seen it or accidentally picked it up and then reported it to the police and my network provider blocked it," she said. "When I got home and went on my laptop, it had also wiped my MACBook.
"I have managed to retrieve what was on my hard drive with a restore, but I am lost without my phone and would love to get it back."
The star made an appeal for the return of the phone, kept in a Louis Vuitton case, on Twitter.com on Sunday (28Feb16), writing, "If anyone does find my iPhone please get in touch It was last seen & used backstage at Manchester Cathedral on Friday. Brown Vuitton case x."