What was going on when I was born?

President Reagan is expected to establish full diplomatic relations with the Vatican and ''in all likelihood'' send a representative there with the rank of ambassador, an Administration official said today. The official said Mr. Reagan would announce the move in mid-January. William A. Wilson, who now serves at the Vatican as the President's personal representative, would probably be the ambassador, Administration officials have said. The President's action was made possible by Congressional passage in November of a law that repealed the 1867 ban on the use of Federal funds to maintain a diplomatic mission to the Vatican. Since then, the Administration has been in touch with Vatican officials on steps to upgrade diplomatic representation.

On the day before the San Francisco 49ers' divisional playoff game against the Detroit Lions, the New Jersey Generals announced today that they had signed two of the 49ers' veteran linebackers, Willie Harper and Bobby Leopold, for the United States Football League season that begins Feb. 26. Harper confirmed his signing before practice here today but regretted its timing. Leopold had no comment. Bill Walsh, the coach of the 49ers, deflected questions about possible distractions and said, ''It's best for me not to remark about it. I'd much rather talk about the playoff game.''

A Federal district judge today blocked the Government's plans to give the public access to 1.5 million of the most confidential documents that were in the White House when President Nixon resigned in 1974. Public release of the documents could theoretically have begun this Tuesday under regulations issued by the General Services Administration. But Judge Thomas F. Hogan held the regulations were invalid because they had been promulgated under a 1974 law that authorized either house of Congress to veto them. Move by 29 Nixon Aides This section of the Presidential Recordings and Materials Preservation Act of 1974 was unconstitutional, Judge Hogan said, under the Supreme Court's sweeping decision last June striking down all such ''legislative veto'' provisions.

The New York Times today publishes an interview with Senator Ernest F. Hollings, another in a series of interviews with candidates for the Presidency. In the interview Senator Hollings made these major points: Economy - Federal deficits must be cut to encourage private investment and re-employment of workers.

Studies of the black family, enough to fill the shelves of a good-size library, focus almost entirely on women. In much of history and sociology, black men, particularly from the ranks of the poor, are ignored. Now, as sociologists, civil rights leaders and government planners focus on the tremendous growth in the number of households headed by black women, nearly 50 percent of all black families, more attention is being paid to the plight of poor black men. Most authorities, and indeed the men themselves, say that unemployment, continuing lags in education and opportunities, chronic illness, racism and jail have left many black men unable to be responsible heads of households. Finding themselves unable to fulfill the traditional male role of provider, many have taken off, leaving the women to raise their children alone, often in poverty. Most experts agree that the causes are complex, and they believe the plight of black men and the increase in poor families headed by women, if unchecked, could be devastating for future generations.

New York State's Chief Judge warned yesterday that the denial of renomination to two State Supreme Court justices by the Bronx Democratic leader could have a chilling effect on other judges who already ''fear for their independence.'' ''They would be worried if they took a stand that might not be popular in a political sense,'' Judge Lawrence H. Cooke said in an interview. In the interview, he outlined an agenda for his final year as Chief Judge of the Court of Appeals, the state's highest tribunal. Judge Cooke also appealed for more financing for the judiciary, because ''we've almost reached the ultimate in what you're asking this system to do.''

Governor Cuomo yesterday ordered state officials to ask 12,000 businesses in New York State to report on where they have been dumping toxic or hazardous chemicals since 1952. Environmentalists said they were ecstatic about the Governor's order, and the state's Business Council said it could live with it, even though its lobbyists had opposed the proposal as burdensome, expensive and difficult to comply with. ''Sound pollution control and emergency-preparedness policies depend on the knowledge of industrial hazardous- waste disposal practices,'' Mr. Cuomo said. ''No systematic industrial survey has been undertaken to ascertain industry's hazardous-waste disposal practices over the past 30 years.''

Jacobo Timerman, the writer and former Argentine newspaper publisher, says he has decided to return to Argentina for two reasons: to try to get his newspaper back, and to bring to justice those who tortured him when he was in custody in the 1970's. Mr. Timerman, speaking in an interview this week at an apartment he keeps in Manhattan's East 50's, said his decision to return, at least for a visit, spoke volumes about how much the situation has changed for the better in the country he once called home. ''For an Argentinian, to go back now, is to see his country in a kind of Camelot,'' Mr. Timerman said. ''After three, four generations of dictatorship, Argentinians are very strongly for democracy. I am amazed, I am impressed and I can't believe it.''

The dictatorship ended nearly three weeks ago when the military stepped down from power, but the mothers who represent some of the thousands of people who disappeared under the military continue their vigil. On Thursday, as they have every Thursday for nearly seven years, several hundred joined in a march of sadness among the flower beds and water fountains of the Plaza de Mayo, in the lee of the pink presidential palace here. Despite the sweltering heat of the Argentine summer, they wore their same white headscarves with the same names of missing children scrawled in ink for all the world to read. ''We will not give up the battle until all the guilty are judged, until we reach the truth about where are our disappeared ones,'' Hebe Bonafini, president of the mothers' group, said in an interview.

Riot troops and mounted policemen charged into a crowd demonstrating against Uruguay's 10- year-old military Government on Thursday night and arrested about 100 people, witnesses said. Several demonstrators were kicked, punched and hit with riot sticks, they said.

Salvadoran guerrillas overran an army base 40 miles north of the capital today and held it for six hours before withdrawing. It was the first time in the four- year-old civil war that the insurgents had overrun a major army installation. A United States official here described the attack as a ''serious defeat'' for Government troops. Salvadoran soldiers coming down from the area told reporters that the base's eight buildings had been completely destroyed in the fighting, and that Government casualties appeared to be heavy. The Defense Ministry said casualty figures were unavailable.

More than 30 Grenadians detained after the United States-led invasion two months ago remain in prison here without formal charges, and the authorities say they cannot yet name a date when the legal process will begin. The continuing imprisonment under a special ''preventative detention'' ordinance is beginning to draw criticism even from Grenadians who support the American presence. They say the absence of democratic processes echoes the repressions of the past. The detainees include Bernard Coard, Deputy Prime Minister in the leftist Government of Prime Minister Maurice Bishop; Mr. Coard's wife, Phyllis, who was in charge of women's affairs, and Gen. Hudson Austin, who led a hard-line coup that resulted in the killing of Mr. Bishop Oct. 19. American troops landed on this Caribbean island six days later.