My computer just freaked!?

I shut my laptop off an hour ago and when i booted it up just now,it went to a screen saying it shut down unsuccessfully and provided four options, three in safe mode, one saying start up normally. i clicked startup normally. it started to load, then said Preparing Desktop. it's never done that before. finally, it finished loading, but the desktop background was one of the defaults, not the one io had set. all my settings were reset. now, i can't pin anything to my taskbar and the start menu is blank. i tried to change my background, and it worked. or so i thought. the picture was set to fit to screen and was all stretched and blurry.i tried to center it, but the background stayed the same! what happened and what can i do to fix it?