Windows 7 starter freezes at Welcome screen

Registration date
Wednesday November 19, 2014
Last seen
November 19, 2014
Hi everyone. I have a problem regarding my Samsung laptop. It worked just fine yesterday but last night, it just restarted on its own and froze at the Welcome screen though the loading icon still kept on spinning. Is it safe to take out the battery when it's still on its welcome screen? I don't know anything about repairing computers so it really upsets me. And yeah, I don't shut my laptop down, i just either put in on sleep or hibernate it. Can someone help me? I can't afford to have it reformatted yet since I still have those important files there and I don't have any back-up. Please help me. Thanks! :)