I have the same problem, yesterday I logged into my Lightroom and I had all my photos, but today when I logged I have seen than more than 1.000 photos were deleted and the same have happen with the presets
I managed to recover all of my lost photos. All of the data was still saved in Lightroom's "Documents & Data" folder. The size of this data folder was around 40 GB so it was easy to identify when it appeared in iTunes' file transfer window.
However, to actually reach and/or copy that data folder, you will need to jailbreak your iPhone and install Filza. Write down the name of that data folder (it's usually something like "kalg28kdo8krkslop8910jd") and then search for it in Filza. Voilá!