What was going on when I was born?

The Reagan Administration has decided to eliminate the Treasury Department's Bureau of Alcohol, Tobacco and Firearms and shift its functions to other Federal law-enforcement agencies, Administration officials said today. The move was explained by the Administration as a budget-cutting measure. Advocates of gun control consider it to be a major victory for the National Rifle Association, which has been conducting a nationwide television campaign portraying the agency as ''jackbooted fascists'' who harass gun owners for technical law violations.

In the years since Russian troops occupied much of Eastern Europe there have been few occasions when the Kremlin has verbally manifested the degree of fury over developments in the Soviet bloc that it did in its letter to Polish leaders demanding that action be taken to end ''anti-Sovietism.'' The letter's existence was confirmed tonight by Tass, the official press agency, nearly 24 hours after it was published in Poland. Tass said the Soviet Ambassador to Poland, Boris I. Aristov, had called on the Polish leaders ''in connection with the provocative activities of antisocialist forces in Poland.'' The agency went on to give an extensive summary of the contents of the letter. Diplomats Wary of Forecasts A similar sequence occurred with the Kremlin's last letter to the Polish leaders, in June, when the Polish authorities released the text, and Moscow, after a delay, followed suit.

Two new crime-fighting programs -one aimed at 6,000 violent, ha bitual street criminals and the other at street robbers in pa rticular - were announced yesterday. Both will emphasize the use of detectives instead of uniformed patrol officers. Police Commissioner Robert J. McGuire said that each program was based on a highly successful pilot project and would require ''substantial shifts in personnel.'' More than 200 officers will be transferred out of uniformed patrols, undercover and narcotics units by Nov. 1 and into detective squads, where they will be known as ''white shield'' detectives. While they will function as detectives, they will not hold gold shields and will not receive a detective's salary.

In recent months several groups of research scientists, working independently, have discovered evidence for the existence of individual genes in the cells of some human cancers that can switch on the cancer process in other normal, living cells. The presence of genes that can cause a normal, healthy cell to turn cancerous and run out of control raises the possibility that future research might discover how to inactivate the genes and, perhaps, short-circuit the cancer-causing process. Scientists working in the field emphasize that such findings might be many years away at best. The genes discovered by the research groups appear to be either aberrant forms of normal ones or genes that have become abnormally activated. Such genes have been found in cells from human leukemia, as well as breast, lung, colon and bladder cancers. In some cases the same gene was involved in more than one cancer type.

President Reagan, defending his economic recovery program in the aftermath of the stock market's plunge to a 16-month low, vowed today to ''fight to the last blow'' for his new round of spending cuts. Once again Mr. Reagan exhorted the financial community to foreswear its ''pessimism'' about the economic plan. He urged Wall Street to respond to the Excerpts from spee ch, page 9. ''rising tide of confidence'' on America's ''Main Street,'' instead of to the statistics that indicated the economy might be approaching a recession.

Elections for at-large City Council members cannot be included in the New York City primary that has been rescheduled for Tuesday, the Justice Department ruled last night. The decision means that no Council seats will be included in Tuesday's balloting, since voting for council members elected by district had already been ruled out. The Justi ce Department, which must rule on any electoral changes inthe Bronx, Brooklyn and Manhattan under the V oting Rights Act of 1965, said it had no objection to holding any citywide or boroughwideprimaries, except for the at-large Council se ats. Sept. 10 Voting Banned Thus, on Tuesday there will be a mayoral primary for Republicans and, for Democrats, primaries for Mayor, City Comptroller, District Attorneys in Brooklyn and Queens, Borough President in Manhattan and a handful of Civil Court jobs. There will also be balloting for judicial delegates and party positions.

The Polish Government warned the Solidarity union today that its actions were jeopardizing the ''independent existence'' of the country. The warning was made at the same time as the authorities released a statement by the Central Committee of the Text of Soviet statement, page 4. Soviet Communist Party telling the Polish leadership that ''anti-Sovietism'' was increasing and that something must be done about it. The statement from the Polish Cabinet, the Council of Ministers, said the Government was prepared to take ''all means'' at its disposal and ''definite measures that might become necessary for the defense of socialism.'' The language was vague but suggested a readiness to use force in any new confrontation with the independent union.

BIG APPLE'S LITTLE APPLES SHINE IN SHOW: Marjorie Tsholakian and her son, David-Aran, admiring city-grown apples on exhibition at the Fall Harvest Festival of the Horticultural Society of New York. The show, which runs through tomorrow, celebrates efforts by backyard, vacant lot and community gardeners.

The House Select Committee on Intelligence has decided to conduct a full-scale investigation of the activities of a former American intelligence agent charged with illegally exporting explosives to Libya, committee members said today. The inquiry, the first by Congress into the case of the agent, Edwin P. Wilson, will examine both Mr. Wilson's conduct and the way the Federal Government has handled the case and related matters, according to committee members. ''This whole case requires an in-depth look,'' said Representative Edward P. Boland, Democrat of Massachusetts, who is the committee chairman. 'Possible Legislative Remedies' Mr. Boland and other committee members said that Mr. Wilson's activities had exposed possible deficiencies in Federal laws governing the conduct of former Government intelligence agents and the transfer of advanced technology abroad. ''We will be looking for possible legislative remedies,'' Mr. Boland said.

Since the return to power of Prime Minister Indira Gandhi, nothing has been as upsetting as the writings of Arun Shourie. The 39-year-old editor, a former economist at the World Bank, is conducting an inquiry into influence-peddling and has brought one of Mrs. Gandhi's most admiring and flamboyant appointees to the brink of resignation. Virtually alone among Indian journalists, Mr. Shourie, an editor of The Indian Express, the nation's largest circulation daily newspaper, has organized and written muckracking exposes on such scandals as the blinding by policemen of 31 suspects awaiting trial, the selling of women and the detention for years of poor people awaiting trial on minor charges. He has written about powerful and politically connected landlords who evade laws that limit holdings.

The police reported more than 1,000 arrests today in the southern state of Tamil Nadu where members of a regional party burned buses and held street protests to demand the release from detention of a party leader. The protesters, members of the Dravida Munnetra Kaghazam, were demanding the release of Muthuvel Karunandhi, the party president, who was arrested on Tuesday at a rally in Madras.

A 2,000-year-old Roman aqueduct has been uncovered during excavation for an automobile plant at Pratola Serra near here, the authorities said today. Alfa Romeo and Japan's Nissan Motor Corporation, partners in the new plant, said they would restore the well-preserved aqueduct.