What was going on when I was born?

China publicly warned the United States today not to sell more arms to Taiwan. It called the issue a ''severe test'' of whether Washington valued its relations with Peking. In a tough but carefully worded commentary, the People's Daily said the United States had ''failed to honor its commitment'' to respect China's sovereignty and had ''resorted to various prevarications'' in the three years since full diplomatic relations were established. The newspaper speaks for the ruling Communist Party, and its commentary amounted to a statement by the Peking leadership. It did not elaborate on the accusations and did not mention the State Department's confirmation earlier this week that the United States intended to sell a multimillion dollar package of military spare parts to the Chinese Nationalists in Taiwan.

The Justice Department, in an unexpected turn, said today that it was trying to settle its antitrust suit against the American Telephone and Telegraph Company out of court. The department joined the company in announcing a resumption of negotiations for a settlement of the Government suit, filed in 1974, to break up the corporation into separate companies. A.T,& T, is midway through a presentation of its case in a trial of the suit that started early in 1981. Judge Harold H. Greene of the United States District Court has said that he hoped to rule as early as July. Many legal experts have considered the outlook grim for A.T.& T. since September, when Judge Greene denied a motion by Bell to dismiss the case. The dismissal request was made shortly after the Justice Department had completed it presentation.

The Reagan Administration has once again changed its plans for deploying the new MX missile, announcing today that at least 40 of them would be placed in existing silos on one of six Minuteman missile fields in the northern high plains. The decision, announced by the Department of Defense, supersedes a plan announced in October by President Reagan under which 36 of the MX missiles were to be based in Arkansas, Kansas or Missouri, in silos now occupied by nearly obsolete Titan intercontinental missiles. An Air Force officer said at a news briefing that the earlier Presidential decision ''looked attractive until you began to see the engineering problems involved.'' Missile Still Experimental Another official said one of those problems was that geological formations around some of the 52 Titan silos apparently made them more difficult to protect against possible enemy attack than was originally believed.

The other day a Polish housewife looked out her window and saw three soldiers manning a roadblock, swinging their arms and stamping on the packed snow to try to get warm. She promptly made a pot of coffee and took it to them. A few hours later, across town, a captain in uniform and a man who looked like a plainclothes security agent barged to the front of the line in the Europejske Hotel restaurant. They demanded, and got, a table instantly while others grumbled. T hese are the people who are going to run Poland, said one young woman with long red hair. The cinkciarz (pe tty thieves).

More than 100,000 children and adults in New York City are likely to lose Federal assistance this year from one or more of a complex of programs that have grown up alongside the food stamp program, according to local officials and groups concerned about nutrition. The people affected are among more than 750,000 New Yorkers who received some kind of supplemental food aid last summer or during the last school year. Federal cutbacks will affect six programs, ranging from the city's 35-year-old school lunch program to the smaller, eight-year old women's, infants' and children's program of medically prescribed nutrition supplements. Just how many people are fed by these programs is impossible to say because they overlap, and the Federal Government does not compile overall estimates. Malnutrition Feared Few suggest that anyone will starve as a result of the cutbacks, partly because many of the people served are already among the city's 1.1 million recipients of food stamps and other benefits.

Many Poles believe that resistance to the martial law Government will take the form of a long, drawn-out struggle involving industrial sabotage, intermittent strikes and some sort of underground organization. There are signs that such a struggle has already begun, and the authorities are reportedly trying to draw up plans to head it off with reforms. The furnace at the giant Katowice steel mill in the south was extinguished by strikers as their final act moments before security forces evicted them last week. To rekindle it is a lengthy and costly operation. In a number of factories around the country, where production was running at less than half capacity for months, work has virtually come to a standstill. Workers simply stand around talking.

Jerry J. Rawlings seized power in Ghana for a second time today, overthrowing the civilian Government that he had resigned in favor of two years ago. In an emotional speech broadcast on Accra radio, Mr. Rawlings accused President Hilla Limann of taking the West African nation ''down to total economic ruin.'' Recalling that he had voluntarily stepped down as Ghana's leader in September 1979 after Mr. Limann and a civilian Parliament were elected, Mr. Rawlings said in his speech that the two years of President Limann's rule ''have seen nothing but repression.'' 'A Pack of Criminals' ''They were a pack of criminals who bled Ghana to the bone,'' Mr. Rawlings, who is 34 years old, said of Mr. Limann and his associates. He said in his radio broadcast that ''several soldiers'' had died in the fighting involved during his coup today. But Mr. Rawlings offered no further details.

The United States has not been able to determine whether Lech Walesa has been negotiating with the Polish authorities. Sources in Warsaw, quoting a relative of Mr. Walesa, reported Tuesday that the Solidarity union leader gave up a two-day hunger strike Christmas Day and agreed to talk with the military Government.

The following dispatch is based on information arriving from Poland. The senior Solidarity leader still at liberty has appealed to soldiers and policemen to ''listen to their conscience'' and not allow themselves to be used ''as tools in the hands of the criminal authorities waging a war against the nation.'' The appeal was handwritten by Zbigniew Bujak, the 27-year-old leader of Solidarity's Warsaw branch, in the form of ''holiday greetings'' to Solidarity members and sympathizers and ''to all our friends in Poland and abroad.'' (The chairman of Poland's Council of State, Henryk Jablonski, called on the nation to preserve the ''sense of national accord'' that he said had grown out of the Solidarity movement. His remarks were made in a televised New Year's speech monitored outside Poland. Page 4.)

Thailand said today that Thai Navy vessels sank a Cambodian gunboat on Monday in Thai waters, killing eight crewmen. Cambodia insisted that the vessel was in Cambodian waters, and said that two Thai warships sailed 10 miles inside Cambodian territory to attack the boat, which was believed to belong to the Vietnamese-supported Government.

Prime Minister Robert Mugabe promised today to step up the redistribution of white-owned farmland among the country's rural blacks.

The Asia-Pacific News Network, formed by the 23-member Organization of Asia-Pacific News Agencies, began operating officially today.