What was going on when I was born?

A picture caption on the front page yesterday misidentified Costa Rica's representative at the Washington meeting of the Organization of American States. He was Foreign Minister

As the Falkland Islands crisis worsens, American companies, which have doubled their investment in Argentina since the mid-1970's, have become increasingly concerned about their operations in the Latin American country. Argentine offices have been told by their parent companies in the United States to restrict travel in Argentina and to maintain a lower profile. These steps are being taken in order not to exacerbate any anti-American feelings that may arise because of the United States Government's historical political commitments to Britain. American companies have some $2.4 billion in direct investment in Argentina and, as the negotiations go on without any settlement, executives are becoming more pessimistic. The suggestion by Prime Minister Margaret Thatcher of Britain on Monday that further military action might be imminent has heightened corporate worries.

The people who would judge John W. Hinckley Jr. looked to the right, to the courtroom's side door, and he came forth today, flanked by security guards, still showing the clean-cut, youthful, slightly anxious gaze that has puzzled the nation since he shot President Reagan 13 months ago. That event, the ''historical deed'' referred to in Mr. Hinckley's own dark writings, convulsed this city a year ago. But this day the defendant and the court did not sift through details of the crime but the far more mundane calendar conflicts and potential prejudices in the lives of the ordinary people on the panel that will produce a jury of his peers. Dressed crisply in a tan summer suit and brown tie, Mr. Hinckley took his seat at the defense table as his trial began and stared forward, facing Federal District Judge Barrington D. Parker and, above on the wall, a white stone statue of Moses handing down the 10 commandments.

ON March 31, Ida Smith was admitted to a hospital in Hartford, paralyzed and unable to speak. The diagnosis was a stroke. Not until almost two weeks later, when a series of tests failed to show stroke damage, did the doctors consider another diagnosis: botulism. The misdiagnosis is not surprising. In 1981 there were only 28 reported cases of botulism in the United States. Most doctors have never seen a victim of the deadly food poisoning. On April 21, Mrs. Smith, 68 years old, who is almost completely paralyzed, was able to respond to simple yes and no questions by clenching her hand. She informed her doctor and officials from the Food and Drug Administration that the day before she became ill she had eaten canned salmon. The questions were not idle guesswork. They were based on an incident that had occurred two and a half months earlier in Europe. A 27-year-old Belgian, Eric Mathay, died of botulism on Feb. 7 after eating a pate made by his wife from a can of salmon imported from the United States. His wife became ill too, but survived.

Secretary of State Alexander M. Haig Jr. said today that, with the Soviet Union entering a period of leadership change, the United States faced ''a historic opportunity'' to influence future Soviet actions by making clear to the Kremlin leaders ''the benefits of greater restraint.'' In a policy speech to the annual meeting here of the Chamber of Commerce of the United States, Mr. Haig stressed the need for the United States to follow simultaneously the paths of strengthening its military forces and pursuing negotiations with the Soviet Union. He criticized what he called the extremes of relying too heavily on negotiations to improve relations or in advocating an ''all-out confrontation'' with Moscow to solve American problems. ''An American approach to the Soviet Union that balances strength and negotiations offers the best hope of significant accomplishment,'' he said in his speech at the Washington Hilton Hotel. ''We must place our policy in the context of important changes that are taking place in the world and in the Soviet empire that may make Moscow more amenable to the virtues of restraint.''

The Exxon Corporation, the world's No.1 industrial company, said yesterday that its net income, hurt by the worldwide oil glut, fell 22.5 percent in the first quarter. This contrasts with an average 20 percent rate of annual growth in Exxon's earnings since 1975. Even starker evidence of the company's difficulties was a 10.6 percent decline in revenues. Officials in Exxon's controller's office said it was the only time that revenues have declined since 1970, the earliest year for which records are readily available. Profits declined in 1981 from 1980, as demand weakened.

An article Saturday about a confer- ence at Brooklyn College on Arts in Transition erred in reporting the com- ments of Leonard Fleischer of Exxon on support of the arts. He said that in 1970 United States corporations con- tributed slightly more than 1 percent of their pretax net profits and that in 1981 the share of all private giving to the arts (including that of individuals, corporations and foundations) was slightly below the 1979 and 1980 fig- ures.

TEN years ago Esther Tuchman, her husband and four children moved from a garden apartment in Bayside, Queens, to a spacious house in Scarsdale. The move seemed ideal, but as it turned out life became tougher for Mrs. Tuchman, for she is one of a number of people who, in a society heavily dependent on the automobile, is afraid to drive. Like many New Yorkers who have grown up in the city and prefer to rely on public transportation rather than bear the burden or expense of a car, Mrs. Tuchman had never found a need to drive. ''We were city people,'' she said. ''My parents never owned a car. In Bayside, the shopping center, the buses, the subway - they were all around the corner.'' But when the family moved to Scarsdale Mrs. Tuchman was confronted for the first time in her life with the necessity of taking the wheel. That is when she discovered that she could not. She tried, she took lessons, but she was still afraid.

Governor Kean forgave nearly $9 million in fines for violations of water- rationing regulations yesterday, as drought emergencies in northern New Jersey and the Delaware River Basin were formally ended. In an executive order issued in Trenton, Mr. Kean directed that $6.7 million in uncollected fines be wiped off the books of water companies and that $2.2 million more in surcharges already paid by penalized customers be applied as credits against future bills. Mr. Kean acted after Monday's rainfall, following winter's abundant rain and snow, pushed the northern half of the state's 12 reservoirs to the brims of the dams or to overflowing. New York City's 18 upstate reservoirs are also full. Water-use restrictions in the city were lifted in January.

''I'm not starving myself or anything. I'm just making a living.

The Organization of American States passed a resolution early this morning calling for a truce in the Falkland Islands and the withdrawal of British and Argentine forces. The nine-point resolution, the product of two days of behind-thescenes negotiations, supports Argentina's claims to sovereignty of the islands. It also ''deplores'' the use of economic and political sanctions against Argentina by Britain and other European nations. But the resolution makes clear that all terms of United Nations Security Council Resolution 502 should be fulfilled. That resolution, adopted on April 3, the day after Argentina invaded the Falklands, calls for the withdrawal of Argentine forces and an end to hostilities.

International Britain will invade the Falklands this week unless an unexpected diplomatic breakthrough occurs, according to authoritative Government sources. Aides to Prime Minister Margaret Thatcher said they saw no evidence of diplomatic progress. The Times of London reported that an advance detachment of British troops had landed in the islands. (Page A1, Column 6.) Argentina rejected a U.S. request for Secretary of State Alexander M. Haig Jr. to return to Buenos Aires to continue his efforts for a settlement of the Falklands crisis. Argentines braced for a British assault against the disputed islands. (A18:1-2.)