What was going on when I was born?

Treasury Secretary Donald T. Regan's tax proposal is being regarded here as less a plan for enactment than a bargaining chip in what is certain to be a prolonged battle with Congress and thousands of special interests over changes in the nation's tax system. Mr. Regan allowed as much today at the news conference announcing the plan. ''This thing was written on a word processor,'' he said. ''It can be changed.'' He said it was the Treasury's proposal, not the President's, and indeed President Reagan seemed to be keeping his distance from the study he ordered last January but saw for the first time only on Monday. In a statement, the President noted the length and complexity of the three- volume report and praised the Secretary for long and hard work. ''Over the next few weeks,'' he said, ''I plan to review the Treasury's recommendations carefully - along with public and Congressional reactions to them.''

A landmark building on Amsterdam Avenue that once housed widows of Revolutionary War veterans would become a low-cost hostel for overnight travelers under a proposal filed with the city yesterday. The proposal, by American Youth Hostels, a nonprofit group with more than 20,000 members in the city, was made to the Landmarks Preservation Commission. It would need approval from various city agencies, including the commission.

Automobile sales improved sharply in the Nov. 11- 20 period, the manufacturers reported here today. Sales by the six major companies jumped 28.8 percent in mid- November from the period last year. Industry analysts said the seasonally adjusted annual selling rate of 7.9 million was near normal, following a strike-induced slump that brought the rate down to 6.9 million early this month and the same level for all of October.

When Congress convenes in January, Republicans will hold the same 53-to-47 majority in the Senate they had in 1981, when they were a driving force behind President Reagan's dramatic legislative successes. But the mood and dynamics now at work among Senate Republicans, who are preparing to choose a new leader Wednesday, are so different from 1981 that many of the Republicans themselves predict Mr. Reagan will have much more difficulty getting his way in 1985 than he did then. In part this is because the Senate increasingly suffers from what Senator Ted Stevens of Alaska, the majority whip, called ''legislative paralysis.'' That involves parliamentary stumbling blocks of filibusters and rump rebellions by which individual senators or small groups stall the work of the chamber, sidetrack major legislation or press their own special agendas. Indeed, ranking Democrats and Republicans are eager to vote institutional reforms to limit and focus debate, impose discipline, give the leadership more power and make the Senate a more manageable, effective body.

Six men have been arrested on charges that they kidnapped a leader of the Unification Church in Manhattan in September and tortured him until he agreed to pay a $1 million ransom, the F.B.I. said yesterday. The church leader, Bo Hi Pak, said he had been held for two days in a small house in Orange County and had been subjected to shocks with electric devices before being released. Two of the arrested men were identified by the F.B.I. as members of the Unification Church and friends of Mr. Pak. None of the ransom money was paid, said Lee F. Laster, an assistant director of the Federal Bureau of Investigation, in announcing the arrests at the bureau's New York office in lower Manhattan.

''I'd like a can of beer.'' - William J. Schroeder, artificial heart recipient. ( B7:1.)

MOST dancers live on diet cola, yogurt and junk food. But Dan Wagoner, dancer and choreographer, is an exception. He eats like a 19th-century farmer: Indian pudding, succotash, buckwheat cakes and Southern fried chicken are the sort of dishes he likes, and he cooks many of them in the fireplace. In an age of food processors and microwave ovens, Mr. Wagoner, who lives in Greenwich Village, is one of a number of people who are returning to old-fashioned recipes and open-hearth cooking. Historical societies and museums report an increased interest in cookbooks and classes on the subject. Cast-iron pots and Dutch ovens, long used for growing geraniums, are finding their way back to their rightful place on the hearth. The 52-year-old Mr. Wagoner, who is the youngest of 10 children of a West Virginia farmer, recalled it this way: ''Where I grew up, all our food, even doughnuts, was cooked on an open wood fire.''

The Scouting column in Sports Pages yesterday gave an incorrect telephone number for a call-in survey to be conducted Saturday by ABC-TV. Those who think Brigham Young University is the No. 1 college football team in the country may call (900) 720-0070.

An article yesterday about an injury suffered by the actor Derek Jacobi misidentified the play to which he will return on Friday. It is ''Much Ado About Nothing,'' at the Gershwin Theater.

Reagan Administration officials said today that Italian and American agents had foiled a possible plan by a group of Lebanese to bomb the United States Embassy in Rome. Italian authorities said they believed the suspects were linked with Islamic Holy War, the group that has taken responsibility for bomb attacks on American installations in Lebanon. In Rome, Police Chief Marcello Monarca said today that seven Lebanese were arrested Saturday near Rome and that one of them had in his possession a detailed map of the American Embassy. He said the map contained notes on supposed ''weak points'' in the large embassy compound.

A white cloud of noxious fumes drifting from New Jersey over the Arthur Kill made at least 32 people ill yesterday on the Staten Island side of the Goethals Bridge. New Jersey environmental officials attributed the situation to a spill of fuming sulfuric acid at a Du Pont plant in Linden, N. J., but the plant manager disagreed. Twenty-three people, most of them suffering from dizziness, nausea and respiratory ailments, were taken to four hospitals on Staten Island, a spokesman for Emergency Medical Services said. The injuries were believed to be relatively minor. Nine others declined treatment.

A.T.&T., the company long known for its warm and friendly ads, has decided to ''reach out and touch someone'' - its competitors - with some stinging ads. As a regulated monopoly, the American Telephone and Telegraph Company sought to increase its business through ads that persuaded people to use the telephone more. Appropriately for a company known as ''Ma Bell,'' it tried to communicate the company's ties to family, friends and home. Now, with the company broken up and competition fierce in telecommunications, the new A.T.&T. is producing some hard-hitting ads that for the first time punch at rivals. At present, for example, A.T.&T.'s nationwide television ads make some not-so-subtle digs at its long-distance rivals, the MCI Communications Corporation and GTE Sprint. The ads, starring Cliff Robertson, note that A.T.&T., unlike the rivals, is the only long-distance company offering operator service and its own connections to small-town America.