What was going on when I was born?

Britain's air and sea blockade of the Falklands began today with ships of the British battle fleet reported in place around the islands in direct challenge to Argentina. The fleet movements were reported by Western military sources here and in London. But the informants said that Argentina and Britain appeared to be waiting for each other to fire first to avoid being accused of starting a war. Military sources here said British destroyers took positions between the Falklands and Argentina on Thursday, hours before the scheduled beginning of the blockade.

American bankers, who have lent Argentina about $9.2 billion, said yesterday that their relationship with Buenos Aires had become far more precarious as a result of the American decision to impose economic sanctions on that country. Although many described the sanctions as mild, they did not disguise their concerns about getting repaid on time. The bankers' concern was reflected in the gold market yesterday, where prices seesawed in reaction to every Falklands rumor. After swinging by more than $30 an ounce, gold ended the day on the Commodities Exchange in New York at $346.50 an ounce, down $14 from Thursday. (Page 33.)

British officials have told the United States that the fleet near the Falkland Islands could sustain operations for 90 days, and the Pentagon has therefore not made contingency plans for resupplying it, Administration officials said today. Secretary of State Alexander M. Haig Jr. said in his statement on the crisis this morning that ''the President has directed that the United States will respond positively to requests for materiel support for British forces.'' ''There will, of course, be no direct United States military involvement,'' he added.

President Reagan met with Republican Congressional leaders today to plan budget strategy amid predictions that Congress would find it extremely difficult to adopt a budget for the next fiscal year. The White House meeting led to a general agreement to use $182 billion as the projected deficit without new taxes or spending cuts in 1983, according to one of the participants. This figure will become the starting point for both sides' proposals on reducing the deficit. Both White House and Senate Budget Committee officials said that the committee was unlikely to approve any reductions in cost-ofliving increases for Social Security, and such reductions are not expected to be approved by the House Budget Committee.

The Tribune Company of Chicago said yesterday that it was ending its effort to sell The Daily News and that it would continue to operate the New York newspaper, which it had threatened three weeks ago to close. The company gave no reason for the sudden about-face. It came after more than four months of concern among readers, advertisers and employees over the future of The News, a morning daily whose circulation of 1.5 million copies is the largest of any generalinterest newspaper in the country. Stanton R. Cook, president of the parent company, told union leaders that they would still be required to negotiate cost cuts to put the paper back in the black. He said, however, that if those talks, due to start next week, were successful, the Tribune Company would invest ''a substantial amount'' in the paper.

Twelve people, including seven children, were killed in Hoboken yesterday in a predawn fire that consumed a small four-story hotel largely filled with women and children. Officials said they suspected arson. And in Jersey City last night, four children died in a fire that spread rapidly through a house in the Greenville section. That fire was also declared suspicious by the authorities. In the Hoboken fire, six of the 37 people in the building jumped from windows to escape the flames before the first firefighters arrived at about 4:25 A.M. from a firehouse a block away. Two of those who jumped were killed, and the four others were hospitalized.

President Reagan accused Argentina today of ''armed aggression'' in the Falkland Islands and ordered limited sanctions against Argentina, placing the United States openly on the side of Britain in the monthlong crisis. Secretary of State Alexander M. Haig Jr. warned that the Falklands dispute was entering ''a new and dangerous phase, in which largescale military action is likely,'' and Mr. Reagan offered to provide British military forces in the South Atlantic with ''materiel support.'' But he ruled out any direct United States military involvement. Secretary Haig said the sanctions against Argentina included a suspension of all military exports and certain forms of new financial assistance. British Position Strengthened Besides the commitment to assist the British with military supplies, Washington's action today was expected to strengthen Britain's political efforts to exert pressure on Argentina for a diplomatic settlement.

A white political party formed in an attempt to improve relations between the black majority Government and Zimbabwe's whites has been disbanded, its leader confirmed today. The party leader, Andre Holland, who resigned from Ian D. Smith's Republican Front Party a year ago to start the Democratic Party, said his group had been unsuccessful in three special elections because whites had become politically apathetic.

President Kenneth D. Kaunda of Zambia ventured to the edge of white-ruled South Africa today and met with Prime Minister P.W. Botha in a mobile home that had been set down in the middle of the African bush across South Africa's border with Botswana. The two leaders were together for nearly four hours and parted amicably after approving a communique of only four sentences. The statement gave not even the slightest hint that they had agreed on any point in a wide-ranging discussion that was said to have focused on the issues of South-West Africa and South Africa itself. Nor did it suggest that the meeting might have practical results.

The Soviet Union is helping Cuba build a nuclear power plant and will raise its aid to Havana over the next five years to its highest level ever, the official Cuban press agency said today. The Prensa Latina dispatch did not mention what type of nuclear plant the Cubans were building, what type of technology was being used or whether the plant would produce plutonium, which is essential for the manufacture of nuclear weapons. Prensa Latina said simply that the nuclear plant would ''form part of the general scheme of electric energy development of the country.''

Two former Secretaries of Defense told a Senate Committee today that they did not accept President Reagan's assertion that the Soviet Union had nuclear superiority. They strongly urged Mr. Reagan to make greater haste in seeking a resumption of nuclear arms control negotiations. The former officials, James R. Schlesinger and Harold Brown, also suggested that American nuclear deterrence might be weakened by statements that the Soviet Union had superiority.

The Roman Catholic Church's top official in southern Africa received a three-year banning order today, the day his first five-year order expired, church officials said. The Government order imposes a kind of internal exile on the official, the Rev. Smangaliso Mkhatshwa, secretary general of the Southern African Catholic Bishops Conference.