SxS cards

I filmed a family wedding on the week-end only to experience panic when I came to download from my sxs cards onto my macbook pro. The XDCAM transfer stated that there were no files to download and a pop up sign read something along the lines "no pars." This happened for both cards. I eventually managed to get one to download so that I could wipe and re-use for the speeches and the evening reception.

During the panic and all the hassle from family relatives, I think I somehow deleted the two files (wedding service) and then reused the disc. There is a saying, we always leave a digital finger print.

My two questions are:
1) Why the pop up message "no pars...."
2) Is there any way a boffin at Sony would be able to retrieve files from a wiped card?

I've just watched Die Hard 4. Any hope for me or should I be grateful that it was a family wedding and not a commercial one.

Mark