What happened...?

I'm hoping someone on the forum can explain what happened to my laptop last night. I was watching a DVD on it and the program crashed so I restarted my computer. This is where the problems started, once rebooted, I initially noticed my background was resetted, all the files saved to my desktop was gone, only the hard drive icon was there and my dock had resetted to the default setting. All my mail is gone, and all the installed applications like Limewire and Adium has to be reinstalled. Anyone knows what would be the cause of this?

Didn't I answer this in another post?

Look in the User folder, how many folders are in there. Looks like you may have somehow booted into another user account

Tell us the folders in hard-disk > User and we may be able to help