Blue LEGO City starter set in box

Yesterday around 3pm I lost my daughter's blue LEGO City starter set. It was outside Liverpool One near the fountain area, just by the Pret a Manger entrance. The box is about 12x8 inches, blue with the LEGO City logo, and the bottom-right corner is a bit scuffed; inside are roughly 120 bricks plus a small red car and a blue minifigure with a white helmet. It has huge sentimental value—it's the first 'big kid' set she bought herself with her own savings, and I really need to get it back for her.