TestDisk is a solid tool. There's a step-by-step guide to undelete file with TestDisk.
While a bit rough to use, I have tried it several times with success -- just be careful as many good tools, it "gives you enough rope to hang yourself".
Alternatively, you can try Photorec from the same site; it's a bit different in principles -- will try to recover everything that was once there and was not overwritten. Slow, sometimes produces junk that "just seemed like a file" to it, but it _will_ find your file, if there's anything left of it.
I may be a bit paranoid (usually when I go for these tools it's either race to save data from crumbling storage or some kind of in-house forensics), but a good practice -- not strictly required to recover data, but maximizing chance of success -- is to make an image of whole device as soon as possible. Then make a copy of that image and work with the copy _only_, so the data won't get overwritten on live machine, and if anything happened to your copy, you can create another from original image.
OTOH, making an image of 16/32GB over USB and keeping at least two copies is slow and requires a lot of space, so it's up to you to decide -- you still have good chance to recover your file even without these steps.