OS X :: My Mac Erased All Its Preferences?

The type of mac we use at our company is an iMac 7,1. There are tons of important files on it. During a routine email in mac mail it was taking a long time so I force quit mac mail. I waited a few moments and when I opened it back up mac mail was asking me to register like I had never used it before!I saved everything and restarted the computer and when the screen came up everything had gone! All my files are still here, thank god, but nothing's in the doc, the mail is asking to be registered, the printers are asking to be registered, and spotlight won't pull up any documents that I know are sitting right in front of me.