All system settings got lost after a reboot

Here is what has happened: I decided to replace a Wi-fi card, installed a CD that came with it, removed the battery, opened the lid, then put the battery back and booted the laptop without closing the lid (just decided to watch a tutorial on wifi replacement again). After this boot I found my system as if it was freshly installed, but with all my files and apps saved. All my configuration of doc, startup apps, dashboard and even iTunes disappeared, iTunes is empty and the other apps behave like they are just installed. I have no idea what caused all this and how to recover.. I didnt do any backups of my system. Maybe you, guys have some suggestions?