In the future I recommend using the aforementioned MC Annihilator to regularly back up full images of your card to USB or HDD, and then if something like this happens as long as you can get into uLE, then you can load MCA and restore the full image (normally, copying FMCB off a card wouldn't work, but if you're doing a full image and restoring it back to the same physical card then the MagicGate keys should match up).
Chip-free homebrew <3
SCPH-39001, FMCB 1.8c, NA+250GB HDD
SCPH-75001, FMCB 1.8c
GSM 0.36 + OPL r639 = Gaming bliss ^_^