What was going on when I was born?

Ontario, Canada's most populous and economically powerful province, is emerging as perhaps the biggest stumbling block to a free trade deal between Washington and Ottawa. ''I'm not prepared to make a giant leap of faith,'' David Peterson, Premier of Ontario, said in an interview. He says he has seen scant evidence that free trade could help Ontario, while he is sure it could hurt in many ways. The Ontario leader plans a trip to Washington in two weeks to discuss his reservations about free trade with Reagan Administration officials, Senators and Congressmen. Next month, he will press them in a meeting with Prime Minister Brian Mulroney and other province premiers.

The Senate, meeting in an unusual Sunday session, today failed to shut off debate on a proposal to balance the Federal budget by 1991. But the Republican leadership said the vote showed that a bipartisan majority supported the legislation. The Sunday session, only the third since 1981 and the fourth in 12 years, came as the Senate worked under pressure to vote on the balanced budget proposal and an increase in the nation's debt ceiling by Monday, when the Treasury Department has estimated it will run out of cash and not be able to pay bills unless the ceiling is raised. Democrats and some Republicans in the Senate have prevented a vote on the budget measure since Friday because they either oppose it or argue that they need more time to consider it. Message From Reagan The Senate met after President Reagan urged its members to move quickly to pass both the balanced budget bill and an increase in the debt ceiling.

International One policeman was killed and 54 others were wounded as black and white rioters armed with shotguns, gasoline bombs and bricks fought with 500 policemen in north London. Officials said the slain policeman, who died from multiple stab wounds in the neck, was the first to die in inner city riots in Britain. The riots was sparked by the death of a black woman who collapsed as police searched her home in Tottenham for stolen goods. [Page A1, Column 4.] The U.S. might support a general capital increase for the World Bank, according to an official who attended a closed-door meeting of leading industrial powers. The increase would permit the World Bank to lend much larger sums to the third world than the $11 billion to $12 billion a year of the last two years. It would also enhance the role of the bank. [A1:5.]

For the first time in eight months, the economy showed signs of improvement in September, the National Association of Purchasing Management said in a report prepared for release today. According to the trade group's monthly survey of 250 purchasing managers at major industrial companies, production levels were up and new orders, the source of future production, rebounded sharply. Inventories rose slightly and the speed of vendor deliveries slowed, an indication that demand is picking up.

As the man forced the woman into a passageway before raping her, he removed a light bulb. In doing so, he left behind a valuable clue - a clear, left thumbprint - that should have quickly resulted in his identification. But the city's Police Department lacks an automated system for speedily identifying fingerprints, so the print on the light bulb remained a mystery for two months last year. In that time, the police say, five more women were raped by the same man, who became known as the Flatbush rapist. A suspect, Gregory Pought, who had been convicted of robbery and whose fingerprints were in the department's master file, was eventually arrested, but not because of the telltale thumbprint.

An article yesterday by United Press International incorrectly reported arrangements for a memorial service for Charles Collingwood, the CBS News correspondent who died Thursday. The 3 P.M. service Wednesday, at St. Bartholomew's Episcopal Church, 109 East 50th Street, is public.

President Reagan is moving toward a decision to formally end United States recognition of the World Court's authority in political cases, Administration officials said today. Officials said the United States would continue to deal with the Court on ''mutually submitted'' disputes involving commercial, legal or border problems with other nations. The officials said that a measure that would withdraw the United States from World Court jurisdiction in political cases had been approved by the National Security Council and that President Reagan was scheduled to sign it either today without making a public announcement, or Monday. The details were quietly drawn up in recent weeks by Attorney General Edwin L. Meese and Secretary of State George P. Shultz and their staffs.

Representative Joseph P. Addabbo, the senior member of New York City's Congressional delegation, has been in the hospital since August, and his absence has left a void that some of his colleagues say could affect both New York's influence on Capitol Hill and the course of national defense policy. Mr. Addabbo, a 60-year-old Democrat representing southeastern Queens, was first elected to Congress the year John F. Kennedy was elected President. In the intervening 25 years, he has risen to the chairmanship of the House Appropriations Committee's Subcommittee on Defense, from which he has exercised considerable influence over military spending. Aides to Mr. Addabbo said they hoped he would be out of the hospital within 10 days, but they could not say when he might be able to return to work. He is being treated for a kidney ailment, they said.

The Advertising Column on Sept. 23 misstated the single-copy sales of People magazine. They averaged 1.6 million weekly in the first half of this year.

When Westway was declared legally dead last Monday, many of the eulogies also mourned the loss of New York's will to conceive and build great public works. But many planners, officials and urban experts are challenging the perception that the project's demise, by itself, signals a fundamental change in government's capacity to achieve grand projects. They agree that there are considerably more procedural constraints, and consequently more judicial oversight or second-guessing, than there used to be. Also, they say, nowadays some officials may be reluctant to risk political capital on projects for which, under the best of circumstances, it is unlikely they will still be in office to break ground, much less cut ribbons. The officials and experts recognize that, after spending 15 years and more than $200 million, there are valuable and enduring lessons to be learned from the Westway experience. Still, some are unwilling to elevate the defeat of the project to a public policy watershed. In fact, developers already are exploring other means of achieving similar ends on Manhattan's West Side waterfront.

''From the opening day of the season,'' Dave Johnson was saying, with a mixture of wonder and regret, ''the Cardinals and Mets have been that close: photo finish. ''We beat them on opening day on Gary Carter's home run in the 10th inning. The next day, we beat them in the 11th inning. Twelve of the 18 games we played them were decided by one run or went extra innings. I think we had to work harder for our wins. But the teams were that close, and that was the story of the season.'' ''The Mets are probably stronger than we are, but not as fast,'' said Whitey Herzog, the manager of the Cardinals. ''And we're extremely different in style. But we're awfully close in results. We beat them 10 times, they beat us 8 times, and that was the chief difference between the teams for the whole season - two games.''

Having failed four times to reach the elite 300-victory level, Phil Niekro decided for his final attempt of the season today to pursue his goal differently. In an astounding switch in strategy and style, the Yankees' 46-year-old right-hander pitched virtually the entire game without throwing his knuckleball, the pitch for which he is famous. The ploy worked, and Niekro became the 18th player in baseball history to win 300 games as the Yankees defeated the Toronto Blue Jays, 8-0. Niekro was the second pitcher this season to reach the celebrated number. Tom Seaver gained his 300th victory pitching for the Chicago White Sox against the Yankees Aug. 4.