Recreate A4 Poster Layered PSD

I have a single flattened A4 poster saved as a JPEG and I need it rebuilt in Photoshop so every element—both the text and the images—sits on its own clearly-named layer. The finished PSD must look indistinguishable... (Budget: £20 - £250 GBP, Jobs: Adobe Creative Cloud, Adobe Illustrator, Adobe Photoshop, Graphic Design, Illustrator, Photo Editing, Photoshop, Photoshop Design)