What was going on when I was born?

Despite a sharp jump in food costs, consumer prices inched up only one-tenth of 1 percent in March, the Labor Department reported today. Prices of most things other than food declined or rose only slightly, and even the recent rapid rise in medical costs slowed. For the first three months of this year, the Consumer Price Index has risen at an annual rate of only four-tenths of 1 percent and is up only 3.6 percent in the last 12 months. The overall price level in the index is now below where it was in October, the first time since 1956 that prices have been lower than five months before.

The State Commissioner of Education refused yesterday to approve Deputy Mayor Robert F. Wagner Jr. as Chancellor of the New York City public school system. The surprise decision by the Commissioner, Gordon M. Ambach, left the largest school system in the country without a permanent chief administrator and threw into doubt when a new Chancellor could be chosen by the seven-member Board of Education. Mr. Ambach said Mr. Wagner lacked the necessary educational requirements for the post and did not have enough educational administrative experience to warrant a waiver. The 39-year-old Deputy Mayor was named Chancellor by the board two weeks ago, but needed the waiver to serve because he does not meet all the formal requirements for the post as they are stated in state education law. The decision was a blow to Mayor Koch, who for weeks had held fast to his choice of Mr. Wagner for the post despite strong opposition from black and Hispanic leaders. The Board of Education selected Mr. Wagner by 6 to 1.

The West German magazine Stern said today that it had discovered 60 volumes of previously unknown handwritten diaries of Hitler and would begin publishing them Monday. The weekly magazine did not say how or from whom it had received the diaries, which it said were written from 1932 to 1945. But it said ''internationally renowned handwriting experts and historians'' had studied the diaries and two volumes of other writings it said related to the flight to Britain in 1941 of Rudolf Hess, Hitler's deputy, and judged them genuine. Other experts said that they doubted that all of the documents could be genuine. These experts have not seen the documents, but have studied the field for years.

President Reagan announced tonight that he was ending the ban on negotiations of a long-term grain agreement with the Soviet Union. He had imposed the ban last year out of concern for the political situation in Poland. Mr. Reagan said he was taking the step ''to reaffirm our reliability as a supplier of grain'' to the Soviet Union. Administration officials explained that the decision came after it became clear that the refusal to talk about a long-term agreement was discouraging the Soviet Union from buying more grain this year.

Farmers here in the ''black muck'' basin on the New York-New Jersey border say they have lost $8 million in damage to their crops and lands from a week of flooding, and more rain is forecast for the weekend. Early crops of onions and lettuce were wiped out when the Wallkill River overflowed and inundated 5,000 acres of some of the richest farmland in the United States. Farther east in Dutchess County, farmers said that damage from the rains that started a week ago was slight, but that the weather had prevented them from planting corn and other crops at their normal times, increasing the chance of frost damage in the fall. Farmers on Long Island and in Connecticut and in lower New Jersey also reported losses. A delay in planting because of the heavy rains, rather than damage to crops, is proving to be the main problem in New Jersey and Connecticut, according to state agriculture officials.

Governor Cuomo said yesterday that he supported President Reagan's effort to withhold taxes from interest and dividend payments, a measure that is under sharp challenge in Congress and from the banking industry. ''I urge you to stay the course on this most important reform of our income tax system,'' Mr. Cuomo, a Democrat, wrote to the President. Aides to the Governor made it clear that Mr. Cuomo was concerned because a repeal of the Federal withholding provision would automatically kill a similar state withholding provision adopted as part of the state budget last month. Mr. Cuomo is counting on the provision to produce $125 million to balance his budget for the fiscal year that began April 1. He did not address this point in his letter.

President Reagan, officially announcing that he is sending Secretary of State George P. Shultz to the Middle East, said today that the ''primary purpose'' of the trip would be to conclude an agreement on the withdrawal of foreign troops from Lebanon. At a news conference, Mr. Reagan also said he believed his overall Middle East peace proposal for dealing with Palestinian problems could be salvaged ''and that's why George Shultz is going there.'' Senior Administration officials said later that the decision for him to go to the Middle East was made after Philip C. Habib, the special Middle East negotiator, cabled a recommendation from Israel on Thursday that Mr. Shultz's direct involvement was needed to overcome the remaining issues in the more than four months of Israeli-Lebanese negotiations. White House Favored Trip The White House also favored a trip by Mr. Shultz to demonstrate the Administration's determination to persevere in the search for Middle East peace despite the bombing of the United States Embassy in Beirut last Monday and the refusal of King Hussein of Jordan to enter negotiations after failing to gain the backing of the Palestine Liberation Organization.

King & Spalding, if not Atlanta's largest or most academically glittering law firm, is by common consensus its most powerful. Its partners include a former United States Attorney General, Governor of Georgia and Presidential confidant and a state bar chief. Its clients, moreover, include Atlanta's corporate colossus, the Coca-Cola Company. But political influence has not spared King & Spalding from a lawsuit that threatens some of the most cherished traditions of America's largest law firms - specifically, the complete autonomy the firms have long enjoyed in selecting their own partners. Recently the United States Supreme Court agreed to hear sex discrimination charges brought against King & Spalding by Elizabeth A. Hishon, who left the firm in 1979 after her partnership bid was rejected.

Europe's highest volcano is active again, spitting forth ponderous masses of molten lava. And as they have done through the ages, dwellers on its flanks stand by helplessly as the inexorable flow crushes their houses, buries their orchards and erases the roads they have built. Two broad fronts of lava have been coursing down the southern slopes of Etna, whose snow-covered summit rises 10,741 feet over Sicily's eastern coast. The eruption began March 27 and has made hundreds of people homeless, destroyed dozens of houses and resort buildings, isolated many others and wreaked untold property damage.

Chancellor Bruno Kreisky, who has headed the Austrian Government for 13 years, said Thursday that if his Socialist Party did not win a clear majority of seats in parliamentary elections Sunday he would step aside. ''For a man in my position, in my situation, it is necessary to know when it is time to go,'' the 72-year-old leader said in an interview. ''And if there is no absolute majority for my party, it's time for a change.''

A five-day Unesco symposium on the news media and disarmament ended today with unanimous agreement on a draft resolution calling on journalists to increase their attention to the issue, delegates said.

The Soviet Union and the United States accused each other again today of prolonging the Conference on European Security and Cooperation, which has been in virtual stalemate for over 30 months, delegates said. Yuri V. Dubinin of the Soviet Union said the conference could fail if the United States refused to change its positions.