After a rocky start to the week, stocks roared back Thursday, giving major indexes their biggest gains of the year. The surge began overseas when the European Central Bank said it’s ready to do more to support the economy and fight deflation. A bit of good news in the United States followed: Fewer people sought jobless benefits last week. And traders think Friday’s jobs report will show gains. ‘The fear in the markets has subsided some,’ said Marc Doss, at Wells Fargo Private Bank. Helping the rally: Disney got a lift from ‘Frozen,’ and the stock rose 5.3%. Dunkin’ said sales are up; its stock rose 3.4%. But Twitter fell 24.2%.