What was going on when I was born?

Equipment breakdowns in yesterday morning's rush hour delayed nearly all 95,000 of the Long Island Rail Road's commuters, including 2,000 who were stranded under the East River for three hours after a train stopped in a tunnel. Thousands of frustrated passengers disembarked during unscheduled stops at the line's Hunters Point station in Queens and headed to subway stations and bus stops for the rest of the trip to Manhattan. But at least as many, having been advised by the railroad of ''a 30-minute delay,'' stayed on board and suffered average delays of an hour and a half to two hours. ''Just about everybody was affected,'' said Alexandra Zetlin of the railroad's public-relations department. The systemwide delays came near the end of an especially difficult winter on the nation's largest commuter line. Railroad officials attributed a rash of breakdowns and canceled runs in December and January to bitterly cold weather. Last summer, chronic airconditioning problems plagued the line.

The Reagan Administration announced today that it had decided to sell additional military equipment to Saudi Arabia as part of a policy of halting a ''serious deterioration'' in Western security interests in the Middle East and Persian Gulf. Contending that there is a ''growing threat'' in the area from the Soviet Union, the Administration said it had decided, over the objections of Israel and many members of Congress, to provide equipment to improve the range and fighting power of 62 F-15 jet fighters purchased by the Saudis. The F-15 Eagle built by McDonnell Douglas is an aircraft designed primarily as a fighter that would have ground-attack ability as well, the State Department said. It was first delivered to the United States Air Force in 1973. Sales to Israel and Saudi Arabia were approved in 1978. Japan will begin receiving F-15's next year.

The possibility that schizophrenia might be caused by a mysterious substance in the blood, and cured by removing it with the hemodialysis technique used in kidney disease, is sustaining a continuing scientific debate about the merits of this costly, dangerous therapy in treating mental illness. A new research report published last week in the journal Science challenges the view that dialysis treatments help schizophrenics, but proponents of dialysis argue that the study is inconclusive and that more research is needed. Dr. Herbert Wagemaker, director of psychiatry at the University of Louisville Hospital in Kentucky, says that he has several patients in research projects who have been ''doing very well for eight or nine years on maintenance dialysis'' treatment for schizophrenia. ''There are only three or four days a year when their symptoms break through and require medication,'' he said. Studies at other institutions have yielded mixed results.

In the Gulf of Fonseca, a Salvadoran patrol launch halts a fishing boat to search for arms.

Continuing large increases in energy prices resulted in a rise of eight-tenths of 1 percent in producer prices in February, the Labor Department reported today. The department also said that the national unemployment rate edged down last month, to 7.3 percent of the labor force, after two months at 7.4 percent. But top Government economists said the Administration still expected a weaker economy in the spring and summer and a marked unemployment rise. (Page 13.)

President Reagan defended increased military aid to El Salvador today, saying that the United States was ''helping the forces that are supporting human rights in El Salvador'' against left-wing ''terrorists.'' Answering five questions on El Salvador at a news conference, Mr. Reagan said that the United States would view with ''the gravest concern'' any right-wing attempt to overthrow the Government headed by President Jose Napoleon Duarte. But Mr. Reagan declined to say whether such a right-wing takeover would result in a complete suspension of United States military and economic aid. And he said that guerrillas who ''boast of having killed somewhere above 6,000 people in the last year'' were the principal human rights violators in El Salvador.

Dr. Bernard W. Harleston, former dean of arts and sciences at Tufts University, was appointed president of City College yesterday by the trustees of the City University of New York, ending a sometimes tumultuous two-year effort to fill the post. Dr. Harleston, a 51-year-old psychologist with a doctorate from the University of Rochester, will be the first black president of the City University's oldest campus, which was founded in 1847. City College is the flagship of what has grown into an educational institution of 18 units with 167,000 students. Dr. Harleston was a dean at Tufts, outside Boston, for 10 years. He gave up the job last summer to take a sabbatical leave and do research on creativity as a visiting scholar at Harvard University.

An imaginary line drawn from Montigny, a drab bedroom suburb to the north of Paris, to Vitry, an equally drab place to the south, would just about pass through Place Colonel Fabian. The French Communist Party headquarters is there, a spiffy glass building designed by Oscar Niemeyer in the days when the party and its intellectuals were on good terms. They are on very bad terms these days, with something approaching a mass defection of artists, writers and scholars to whom Vitry and Montigny stand for a terminal betrayal. Vitry-sur-Seine and Montigny-les-Cormeilles are old working-class strongholds and bastions of the Communist Party. In recent years a large African immigrant population has moved in. Playing upon the fears and prejudices of their supporters, party officials have taken spectacular and harsh action against the immigrants in both towns.

Polish troops moved out of their barracks today in apparent preparations for major maneuvers, but Western military attaches said there was no sign that they had linked up with troops from the Soviet Union or other Warsaw Pact forces. Thousands of troops were seen leaving garrisons outside several major cities, including one at Rembertow, a suburb east of Warsaw. Their destination was not known. Military sources said they had no idea how large the maneuvers would be or what outside forces might be involved. But they added that at this point they had no reason to believe that the exercises were intended for anything other than training purposes.

International trade in the oil, meat and bones of three species of whales was outlawed here today over the opposition of Japan, while the United States and the Soviet Union abstained in the vote. Since the three species - the sperm, sei and fin whales - are virtually the only whales still hunted by commercial fleets, today's action was applauded by conservationists as a major step to preserve dwindling whale populations. ''Hooray!'' declared Craig van Note, a Washington-based advocate of the protection of whales who represents a coalition of ecologists and naturalists called Monitor. ''What we've done here is carried the fight still further and removed a good deal of what remains of the economic motivation for whaling.''

Hijackers today fatally shot a Pakistani diplomat being held hostage aboard a Pakistani jetliner in Kabul, the Afghanistan radio said. At the same time, the radio said, the three hijackers set 3 P.M. tomorrow as the new deadline for Pakistan to meet demands for the release of 115 hostages still aboard the aircraft. The hijackers want Pakistan to release inmates who they say are political prisoners.

President Reagan said today that he had asked the Senate to ratify an East Coast boundary treaty with Canada but that he had at the same time asked it to drop consideration of a proposed fisheries agreement. The fisheries agreement would establish limits on catches for various species of fish and shellfish, limits that United States fishermen opposed. The draft treaty, covering both the boundary and fisheries questions, has been held up in Congress since it was signed and submitted for ratification by President Jimmy Carter two years ago.