What was going on when I was born?

States across the country are passing laws to crack down on parents who fail to pay child support. The laws give judges and other state officials stronger tools to enforce orders requiring parents who live apart from their children to contribute to their support. Among the new measures are provisions for seizing income tax refunds or withholding wages from people who fall too far behind on child support. Federal Standards Set ''There is a tremendous amount of activity in state legislatures addressing the issue this year,'' said Fred Schutzman, the deputy director of the Federal Office of Child Support Enforcement.

The City Department of Correction said yesterday that it would ask Federal immigration authorities to screen more carefully the detained aliens it sends to a Brooklyn jail where a dozen Cubans awaiting deportation attacked and injured 18 guards Saturday. A department spokesman, Edward Hershey, said city officials would urge United States Immigration and Naturalization Service representatives at a meeting today to change the procedures that allowed the Cubans, all of whom have criminal records, to be transferred to the Brooklyn Correctional Facility. The minimum-security jail on the site of the former Brooklyn Navy Yard brig, at 136 Flushing Avenue in the Fort Greene section, houses about 200 prisoners in dormitories. In the violence Saturday, one prisoner punched a guard during the morning roll call and others began throwing lockers and other furniture at unarmed officers who were called to help, Mr. Hershey said.

For two weeks he beat a path on the grass courts at the All-England Club, defying tennis tradition and the logic that said he was too young to win. Boris Becker argued logic with a serve that earned him the nickname Boom Boom, and ignored tradition with the irreverence of youth. And today, the 17-year-old from West Germany wrote a storybook ending when he became the youngest champion in the history of the men's singles at Wimbledon. Playing before a crowd of 15,000 at Centre Court, on a worn surface that was more dirt than grass, Becker defeated Kevin Curren, 6-3, 6-7, 7-6, 6-4, in a match in which the serve was often too quick for a reply. Becker had 21 aces and Curren 19 and there were stretches during the match when there was no need for a player on the other side of the net.

Six huge airlines with the power to control fares and routes could emerge from turbulent forces that are reshaping the industry, many Wall Street analysts and airline executives believe. If they are right, such a concentration in a business that now has a dozen or so major participants would severely undercut the competitive forces that legislators sought to unleash when they approved deregulation of the airline industry in 1978. Many top airline executives have asked their staffs to investigate possible mergers with other companies or acquisitions of international routes. Others, such as American Airlines, think mergers can bring more problems than they solve and plan to rely on internal expansion to keep up with the competition. If a trend to fewer and bigger airlines develops, the fare wars that have wreaked havoc within the industry in the past few years could diminish, some analysts believe.

Vietnam has promised to return the remains of 26 more American servicemen who died in the Vietnam War, the largest such turnover since the fighting ended, Americans officials said today. Officials traveling with Secretary of State George P. Shultz on a tour of Southeast Asia and Australia appeared surprised and delighted at the commitment, which was made to a United States military casualty research group that just ended a three-day mission to Hanoi. Visit With Cambodia Rebels On Monday, Mr. Shultz will meet with Thai officials in Bangkok, and on Tuesday he will visit a Cambodian refugee camp inside Thailand on the border with Cambodia. United States officials said Mr. Shultz would meet with two leaders of Cambodia's non-Communist resistance movement in Bangkok.

''Save on calls down under,'' says GTE Sprint in advertisements promoting Sprint's recently inaugurated long-distance phone service to Australia. An MCI ad showing a family of penguins in the Antarctic says, ''This is the only continent you can't call right now with MCI International.'' An A.T.&T. television ad filmed in Italy shows a doleful, American teen-ager bidding farewell to her Italian boyfriend. A voice in the background offers a cheerful note: ''Saying goodbye is never easy, but saying hello is, with A.T.&T.'' So goes the marketing in the latest push in telecommunications competition: international long distance. Having broken the monopoly on domestic intercity calling, A.T.&T.'s cut-rate rivals are trying to repeat their success in the business of calling abroad. While the American Telephone and Telegraph Company still controls roughly 97 percent of that $5 billion market, most industry analysts say the percentage could shrink quickly as A.T.&T.'s rivals intensify their efforts in a rapidly developing marketing war. ''The U.S. business customer is used to thinking about competitive carriers,'' said Mary A. Johnston, a long-distance industry analyst at the Yankee Group, a Boston-based research firm. ''If they can get reasonable quality service for calls abroad, there is no reason they should not go for the low-priced carrier.''

International Vietnam has promised to return the remains of 26 American military personnel who died in the Vietnam War, United States officials said. The promise followed a proposal by the Vietnamese to begin talks aimed at clearing up the question of missing Americans within the next two years.[Page A1, Column 3.] The president of Guinea said that the leader and co-conspirators of a coup attempt against him would be executed by a firing squad. The President, Brig. Gen. Lansana Conte, told an audience of more than 50,000 people gathered in front of the People's Palace in the Guinean capital of Conakry that the coup leader, Col. Diara Traore, had been arrested.[A1:1.]

International OPEC oil ministers failed to agree to any changes in pricing or production after three days of meetings in Vienna. Oil industry analysts, oil company executives and some oil ministers said the lack of a clear solution to the group's problems could lead to a further decline in oil prices. However, the 13-member organization will meet again July 22 in Geneva, where some of the suggestions made over the weekend may be discussed again. [Page A1.] Competition for international long-distance calls is heating up as A.T.& T.'s rivals fight to cut into the telephone giant's 97 percent share of the $5 billion overseas market. [D1.] Sinking oil platforms may threaten European gas production from the Ekofisk field in the North Sea. [D1.] High-technology investments by foreign companies in Malaysia have disappointed officials there, who had hoped for greater stimulus to local development. [D4.] Canada's grain farmers are facing a quiet crisis as pests threaten crops and worldwide oversupply hurts prices. [D4.] The Economy Economic activity among manufacturers continued to sag last month, the nation's purchasing managers reported. They said overall activity last month fell to its lowest level since December 1982 -a finding that was in sharp contrast to other recent reports that suggest the economy may be regaining lost momentum. [D1.] Companies Six huge airlines could result from industry consolidation, according to analysts and airline executives, who said the giant carriers would have the power to control fares and routes.

Six days ago, the Mets had tumbled all the way to fourth place, their season reduced to a six-game losing streak and their offense slumbering quietly in the final days of June. But so much has happened since then. The losing has stopped, the offense suddenly is rejuvenated, Ray Knight is hitting again and a new starting center fielder is igniting the offense. There was room for optimism late today after the Mets won their sixth straight game and swept the four-game series from the Atlanta Braves by sweeping a doubleheader, 4-0 and 8-5. After falling as many as five games out of first place, they have climbed to within two and a half.

In 1979, Neiman-Marcus, the Dallas-based luxury retail store, offered a satellite dish antenna that, for $36,500, would provide a cornucopia of television programming, including ''10,000 top movies a year'' and ''sessions of the United States House of Representatives.'' Not one was sold, but the point was made: the satellite dish, which could receive signals from space, was coming to the American home. In the last six years, more than a million Americans have bought satellite dish antennas - now starting at $2,500 - and pointed them toward the satellites carrying the pictures and sounds that are the commercial capital of the communications industry. The dishes can intercept programming that far exceeds even the most complete cable system's, catching signals from as many as 150 broadcasters. Some of it is not intended for the home-viewing public, such as blacked-out sports events, video business meetings or, in one instance, when a network was tuning its cameras from the White House, an unsanctioned view of the President of the United States.

Economic activity among manufacturers continued to sag last month, the nation's purchasing managers said in their latest report, released today. The report that overall activity last month fell to its lowest level since December 1982 contrasts sharply with other indicators suggesting the economy may be regaining lost momentum. ''We keep looking for an upsurge, but we don't see it,'' said Jerry Baker, executive vice president of the National Association of Purchasing Management, which conducts the monthly survey. ''There just doesn't seem to be any strength.''

In Delray Beach, Fla., last February, Boris Becker was just another promising player on the tennis tour. He walked the grounds of the condominium complex where he was staying, wearing stereo headphones and listening to music, unnoticed by those around him. He was a teen-ager far from home yet comfortable in unfamiliar surroundings. ''In Germany, my classmates are reading about the United States,'' Becker said then. ''And I am here learning for myself.''