I'm going to presume that as you've posted in the root subforum, you're rooted? You can try searching the phones internal memory with root explorer, you might be able to find it there somewhere. I've had a look on my handset and I can't seem to find mine though.
If you're happier searching via the PC, you can also browse the handset memory via
MyPhoneExplorer. Just be careful you don't delete/move ANYTHING
If you still can't find it that way and you're not rooted, if you're desperate to get the picture back, you can take a screenshot of your device with the SDK, or alternatively, using the MPE app I mentioned above. Clear all icons from your homescreen, connect the phone via usb open MPE, select the extras menu, then load screenshot. You should be given the option to save it.
It's a bit of a poor workaround, but you'll at least have the photo.