What was going on when I was born?

The Organization of Petroleum Exporting Countries, moving to reduce the worldwide surplus of oil and bolster prices, agreed today to cut production by about 700,000 barrels a day. It was the first formal production agreement by the 13 OPEC members. The reduction was greater than had been expected, and included a cut of 500,000 barrels a day in Saudi Arabia's production ceiling, to seven million barrels a day. The action would reduce OPEC's total daily output to a maximum of 17.5 million barrels a day, from its estimated current production of 18.2 million barrels. Only three years ago OPEC was producing 31 million barrels of oil a day.

The Reagan Administration said today that it had information that three months ago Fidel Castro, the Cuban leader, ordered a step-up in arms shipments to insurgents in El Salvador in an effort to disrupt the March 28 elections there. The State Department also said it had learned that after a meeting in Havana in mid-December between the Cubans and Salvadoran guerrilla leaders, ''extreme leftist groups throughout Central America were mobilized to support the effort.'' A department spokesman declined to make public the source of its information, saying it was based on sensitive intelligence data the release of which would compromise sources and possibly endanger the lives of intelligence operatives. However, along with the report the department released a compendium of comments in support of the charges of Nicaraguan involvement from ''distinguished Americans'' who it said had seen the secret evidence.

It is midnight on a Saturday night, and the cabaret at Palsson's Upstairs is crowded. The lights dim and the spotlight shimmers against the backdrop, a glittering curtain of tinsel. To the tune of ''It's Almost Like Being in Love,'' Gerard Alessandrini and Nora Mae Lyng deliver their verdict on Broadway's reliance on the tired old tried-and-true: ''The backers who finance a show All agree people like what they know So instead of what's new They just redo the few That were famous in 1940 - Not more than 1950 - Almost like 1948.'' The song is one of many in ''Forbidden Broadway,'' a satirical Off-Off Broadway revue that skewers Broadway hits and their stars. Whatever the merits of its charge that Broadway suffers from a derth of fresh ideas, the same could hardly be said of Off Broadway and Off Off Broadway theater. ''Forbidden Broadway'' is packing them in on West 72d Street, while a bumper crop of plays and musicals is flourishing at smaller theaters all over town. Meanwhile, however, Broadway is limping through a troubling season. An ominous number of Broadway closings has coincided with an unusually long dry spell between major openings, and the contrast with the creative ferment elsewhere seems particularly marked. ''Off Broadway really is where most of the excitement is,'' says Bob Gunton, the star of ''How I Got That Story,'' which is currently ensconced at the Westside Arts Theater.

EQUITY theater in the county may temporarily be a thing of the past because of the cancellation of the last three plays of the 1981-82 season of the Main Street Theater company in White Plains, Westchester's last Actors' Equity troupe. But that professional acting group's artistic director said he not only was encouraged about the future of theater as a whole in the county but also was extremely hopeful that the closing of his group would be temporary. His comments shed light on the dilemma created, on one hand, by the closing of a number of theaters in the county in the last few years and, on the other, by the presence in the area of many sophisticated, highly educated, well-to-do would-be theatergoers with no place to go nearby. Stephen Rosenfield, the artistic director of the Main Street Theater, in an interview last week in his brownstone apartment on Manhattan's East Side, said that his board of directors, although making the decision to cancel the season, had still reserved the option to continue the theater company's performances when new money could be obtained. (The plays omitted were Noel Coward's ''Private Lives,'' Chekhov's ''Uncle Vanya'' and a comedy that had not been selected.

IN every direction, as far as the eye can see, the unmistakable imprint of Japan's largest auto maker is evident in this city that fittingly bears the company name. More than 35,000 of the Toyota Motor Company's 48,000 employees worldwide work here, 150 miles west of Tokyo. Rows and rows of lookalike houses that Toyota provides for its married workers at cutrate prices form a kind of corporate Levittown. Company dormitories can house 20,000 bachelors and another 1,500 units are available for unmarried women workers. Then, too, there is the company stadium that seats 30,000, the company baseball fields, the company gymnasiums, the company swimming pools, company tennis courts, even company sumo rings.

Real estate brokers and homeowners are agreed that attractive houses can still be obtained in the metropolitan area at moderate prices. All that is required, according to brokers in Westchester County and on Staten Island and Long Island, is a little patience and flexibility in tracking them down, in any number of low-profile communities in the area. David and Marguerite Hankins found the kind of house they wanted at a price they could afford in just such a community. When they decided to leave their small, two-bedroom apartment in Brooklyn Heights last spring, the Hankinses felt they could not afford a large enough co-op in the city, and liked the idea of raising their two young children in a quiet town in the suburbs. Their best friends had moved to Westport, Conn., so they looked there. They were prepared to spend up to $80,000. But the only house they liked that was anywhere near their price range was selling for $105,000.

BROOKHAVEN FOR 15 years, Michael Adams had a dream. A builder who lives in Dix Hills, Mr. Adams bought 13 acres in Blue Point with 830 feet of shoreline. He planned to build a motel and restaurant there with a swimming pool and jetties for the sailors to moor their boats while they dined. He also planned eventually to retire there with his wife, Nealy. Mr. Adams's dream ended two months ago when the State Department of Environmental Conservation condemned his land, part of a 35-acre acquisition of wetlands along Stillman Creek that was announced on March 10. The acquisition was necessary, department officials said, because the tidal marsh, which will be open to the public, is important to the life cycle of shore birds and the fishing and shellfish industries of the Great South Bay.

-------------------------------------------------------------------- Audrey Topping is the author of ''The Splendors of Tibet.'' BY AUDREY TOPPING Visitors to the Metropolitan Museum beginning April 3 will have an opportunity to walk through a simulated Buddhist cave temple and see original fragments from ancient wall frescoes, painted temple hangings and exquisite clay sculptures that were excavated from the desert sands of Central Asia after being buried for almost a thousand years. This loan exhibition will continue through June 20. These rare religious treasures will be shown for the first time in the United States. The exhibition, called ''Along the Ancient Silk Routes: Central Asian Art From the West Berlin State Museums,'' will offer the viewer a unique insight into the exotic art of a virtually unknown chapter of Central Asian history.

IN an effort to convert last year's $2.6 million operating loss into a profit, Playland officials have announced a new admissions policy and other changes for the season this year. At a meeting with members of the county's Board of Legislators, officials of the Marriott Corporation, which manages Playland, unveiled a new $7.95 unlimited-rides ticket, called ''Ticket to Ride.'' Marriott's plans for this year also call for the addition of three new rides, an improved food service and an expanded selection of souvenirs. The hours at the park will change slightly as well, reflecting the need for school groups to come to the park at an earlier hour.

IN 1974, State Supreme Court Justice Joseph F. Gagliardi ruled that a lawyer could not be compelled to take a case without fee. Such a court order assigning counsel without compensation, he wrote, would violate a lawyer's constitutional right to due process of law. Eight years later, Justice Gagliardi, now the administrative judge for the county's court system, has reversed himself. Justice Gagliardi recently asked the judges in his jurisdiction to order such assignments in divorce cases for persons able to demonstrate indigency. In the wake of last year's Federal budget cuts, the poor can no longer get a lawyer to handle their divorces free of charge from Westchester Legal Services, the local outlet for federally financed legal aid in civil cases.

IN REDDING and Wilton, local newspapers have editorialized strongly in favor of continued student aid. In Easton and New Canaan, legislators have virtually been buried under letters and phone calls pleading for action. And in Hartford, liberals and conservatives have lined up with administrators from private and public colleges behind proposals that could make Connecticut the third state to establish special bonding authorities for student aid. Illinois and Massachusetts have also approved such programs. The issue is student loans, and the demand for action by the General Assembly and the state's Department of Education has surged, making replacement loan programs for cuts in Federal student aid one of the most talked about issues since the education equalization formula altered state-aid commitments in 1979. Faced with enacted and proposed Federal cutbacks in aid that will mean Connecticut students could lose $3.4 million in loans in 1982 and possibly $17 million more by next year, middle-class residents have demanded action.

FAIRFIELD ONLY 17 of the 933 delegates to the Republican State Convention in July will be chosen here on Tuesday, but the party's candidates for United States Senate and Governor are treating the town of Fairfield as if it were New Hampshire in a Presidential election year. From early-morning handshakes with commuters at the train station, to walking tours of neighborhoods and businesses, to appearances and speeches at any available public gathering, the Republican Senate and gubernatorial candidates are spending almost full time here these days trying to woo the 11,000 or so enrolled Republicans who are eligible to vote next Tuesday in the only ''open'' caucus among Connecticut's 169 towns. ''After Tuesday, we'll never see them again,'' Fred H. Lovegrove Jr., chairman of the Republican town committee, said of the candidates. ''They'll either have us, or they won't,'' he added with a chuckle. For the main candidates, such as Senator Lowell P. Weicker Jr., who is being challenged by Prescott Bush Jr., the brother of Vice President George Bush, and the four Republican gubernatorial candidates, the importance of the Fairfield caucus is that it will be the first public test of their strengths among Republican voters.