What was going on when I was born?

President Reagan said today that he had decided to seek development of an advanced missile-defense system because it was ''inconceivable'' for the United States and the Soviet Union to continue indefinitely to threaten each other with nuclear destruction. Mr. Reagan, at a news conference at the White House, said the Soviet Union and the United States had become ''like people facing themselves across a table, each with a cocked gun, and no one knowing whether someone might tighten their finger on the trigger.'' He acknowledged that the situation had prevented one side from attacking the other for decades. But he said he thought ''there is another way'' that peace might be preserved - for scientists to ''turn their talent to the job of perhaps coming up with something that would render these weapons obsolete.''

A Presidential panel has authorized the Army Corps of Engineers to seek major changes in the law protecting the nation's wetlands. Page 8. WASHINGTON, March 25 - The Reagan Administration announced the resignations today of five senior officials of the Environmental Protection Agency, including Acting Administrator John W. Hernandez Jr. The chairmen of all the House subcommittees investigating the agency's conduct said after the announcement that they intended to proceed with their inquiries.

In the latest of a series of charges that have created the impression abroad that Nicaragua is under siege, the Sandinist Government said today that Honduran troops entered its territory Thursday but were driven back after an exchange of gunfire. (In Tegucigalpa, the Honduran capital, a Foreign Ministry spokesman termed the Nicaraguan accusation ''totally false.'' Page 3.) Protest at the U.N. The charge against Honduras followed Nicaragua's protest this week to the United Nations Security Council that United States-backed exile bands based in Honduras had stepped up their incursions into this country. In addition, the armed opposition has claimed to have captured several Nicaraguan villages. Yet despite their increasing military actions in the last few months, rebel bands appear to have attracted little public support in Nicaragua, according to the evidence available to reporters here. This is believed to be because of the Honduran-based rebels' identification with the unpopular national guard of the Government of Anastasio Somoza Debayle, which the Sandinists overthrew in 1979.

New York City's Board of Education is discussing ways to limit the powers of the next Chancellor and expand its own authority over the city's public school system, the board president said yesterday. ''We're assessing the priorities, reassessing where emphasis should be, reassessing where we can get a tighter situation than what we have now in certain areas,'' the board president, Joseph G. Barkan, said in a telephone interview from his vacation home in Florida. It has been years since a board has so aggressively considered asserting its authority over the city's public school system, which, with a budget of more than $3 billion, nearly a million students and a staff of 100,000, 55,000 of them teachers, is the largest in the nation. It is happening now, many board members say, because they have been so overshadowed by the last Chancellor, Frank J. Macchiarola.

France's Socialist Government adopted a tough austerity package today in a bid to resolve its economic crisis. Included were a limit on the amount of money that tourists can take abroad and a ''forced loan'' that most income tax payers will have to make to the Government. The package is intended to reduce consumer spending this year by 65 billion francs, or $9 billion, the equivalent of 2 percent of France's gross national product, the annual output of all goods and services. Such a cutback was aimed at restoring confidence in the franc by reducing inflation as well as the nation's huge trade deficit.

The latest draft report by a committee of Catholic bishops reaffirms their antinuclear stance. Page 7. WASHINGTON, March 25 - The Federal Bureau of Investigation has determined that the Soviet Union does not ''directly control or manipulate'' the American nuclear freeze movement, according to a declassified version of the report released today. ''Based on information available to us, we do not believe the Soviets have achieved a dominant role in the U.S. peace and nuclear freeze movements, or that they directly control or manipulate the movement,'' the report concludes.

There is a quiet sense of tension and intellectual ferment here as the people of this capital await King Hussein's decision on whether he will join Middle East peace negotiations on the basis of President Reagan's proposals. Interviews here suggest that Jordanians are divided on the Reagan initiative and the pivotal role it would give to this country, with their views determined largely by the side of the Jordan River on which they were born. Fears of East Bankers Most of those known here as East Bankers seem to fear that Jordan is being asked to venture out on a limb for the sake of the Palestinians in the @Israeli-occupied territories, for whom President Reagan has proposed autonomy in association with Jordan. East Bankers who were interviewed said the move would defy Arab public opinion with no guarantee that the Israelis would budge from the occupied West Bank.

A Federal judge ruled today that the Exxon Corporation overcharged customers between 1975 and 1981 in violation of Government price controls. He directed the company to refund a total of $1.49 billion. This sum comprises overcharges of $895 million and an estimated $600 million in interest. It would be allocated to state governments under a formula based on consumption of oil products during the period when price controls were in effect.

Yuri V. Andropov met at the Kremlin today with Daniel Ortega Saavedra, coordinator of Nicaragua's junta. The meeting was the Soviet leader's first announced engagement in 11 days and appeared to end the uncertainty that developed when rumors swept Moscow that he was ill. Some reports said Mr. Andropov, 68 years old, who succeeded Leonid I. Brezhnev as Communist Party leader in November, was suffering from a kidney ailment, but a senior official said it was nothing worse than influenza.

The Venezuelan national anthem calls on citizens to ''follow the example of Caracas,'' but if they did so today, the country would become one fed on Chinese cooking, transported in eight-cylinder American limousines and dressed in Italian designer clothes. ''When I go into a store and ask if something is good, the answer comes back, 'Oh, yes, it's imported,' '' said a French woman who lives here. An exhibition that opened March 17 honoring Simon Bolivar, the country's most cherished national symbol, is mounted on panels brought here from Switzerland. Much of the money that poured into Venezuela during its oil boom went to buy foreign things and in the process converted Caracas into a metropolis of office towers and modern apartment buildings with little feel of its region. ''They've changed around the Plaza Venezuela five times in the last 30 years,'' Andres Duarte Vivas, a businessman here, said of one of the city's historic squares.

President Reagan emphatically defended Kenneth L. Adelman, his nominee to head the Arms Control and Disarmament Agency, today and said Mr. Adelman's Senate critics were ''smaller than the person they're attacking.'' ''You bet I'm sticking by Mr. Adelman,'' the President said in response to a question at a brief White House news conference. The nomination has been bogged down in the Senate by weeks of controversy about Mr. Adelman's qualifications, with Democrats and Republicans charging that his private memos contradict his Senate testimony on the subject of a possible personnel purge at the disarmament agency.

Nearly 250 people were under arrest here today after violent protests Thursday night against the military Government of President Augusto Pinochet. Policemen used water cannons to battle hundreds of rock-throwing protesters for more than an hour in a 20-block area. Diplomats here said it was the first time the cannons had been used since 1973, when General Pinochet overthrew the Marxist Government of President Salvador Allende Gossens. The protests reportedly were organized by the Communist Party Youths, an outlawed organization, and the police said most of those arrested were youths. But many office workers and shoppers joined in jeering the police, chanting, ''Pinochet, assassin!'' or ''Work, bread, justice and liberty!''