I'm thinking maybe a simple undeleter program would suffice, but that depends if it'll read from a memory card (thats if it wasn't on an internal memory), and you have a memory card reader on your PC that you can open up.
Since no data is actually deleted from anything, as long as the place where the data was hasn't been overwritted with something else after deletion.
If the memory card acts as an external storage device and appears as a drive in windows, theres hope.
Try this program. Its free. I don't truely know how good it is, since I've never had to use it, but who knows?:
If its internal, though, with no drive, your screwed I'm afraid, as I don't know of a program that'll allow you to search for files on the device itself, needing firmware support, etc.