What was going on when I was born?

The New York City Department of Health said yesterday that the flu that arrived here in November had reached epidemic proportions and that it would probably get worse in the next two weeks. Hospital clinics and emergency rooms throughout the city, particularly in the Bronx, were reported crowded with patients suffering from what has been designated as the A-type Bangkok strain of influenza, a relatively new type of flu virus isolated in Asia two years ago. Like other strains of flu, the Bangkok variety produces fever, headache, runny noses, body aches, sore throats and sometimes nausea and vomiting.

Ayatollah Ruhollah Khomeini gave his approval last night to Algerian assistance in efforts to release the 52 American hostages, raising new hopes for a solution to the 14-month-old crisis with the United States. The Ayatollah's endorsement - necessary for any major move - was announced during the evening by Prime Minister Mohammed Ali Rajai after a meeting with the revolutionary leader. But the precise terms of the Algerian role and the state of the negotiations remained unknown, and Mr. Rajai's remarks themselves created further confusion and uncertainty. Ambiguous Term Causes Confusion The confusion stemmed from the Prime Minister's use of the Persian word ''tahod,'' which can be translated as meaning either ''undertaking'' or ''guarantee.'' In the context of his remarks, the difference is critical.

Donald T. Regan, Treasury Secretary-designate, predicted today that the economy would decline this year but that ''major improvement'' would occur within 15 months if Presidentelect Ronald Reagan's economic program were adopted. Mr. Regan offered no specific forecast, other than to say that the recovery may be ''aborting'' and that the gross national product, after adjustment for inflation, would probably shrink in 1981. He conceded, however, at his confirmation hearing before the Senate Finance Committee, that the incoming administration's target for a balanced budget had slipped a year, to 1984, as the outlook for the budget deficit has steadily worsened in recent weeks. Carter Administration officials, meanwhile, said today that their projected deficit for 1981 had taken another leap, to nearly $60 billion. Administration and budget experts said that the addition of a tax cut by President-elect Ronald Reagan could push the deficit past the previous record of $66.4 billion set in the final year of the Ford Administration.

The Tandy Corporation is back in Wall Street's favor, just two years after the company's reputation as a star growth company lay in shambles. The abrupt collapse of the citizens band radio craze in 1977 hit hard at Tandy, the market leader through sales in its Radio Shack chain. Net profits declined 4.2 percent in the fiscal year 1978, a disastrous performance for a company that had expanded continuously during the 15 years in which Charles D. Tandy had built the 9-store chain to 7,000 outlets. Some analysts predicted a bleak future for the company, but Tandy executives found a solution to the corporate problems in a new hightechnology consumer product, the microcomputer sold for use in homes and small offices.

German veterans come to bury, and to praise, Doenitz A2 Japanese Prime Minister plans trip to 5 Southeast Asia nations A3 Senator Stevens and Chennault meet with Taiwan's President A3 United States reporter is missing in El Savador A3 Around the World A5 Kissinger urges enhanced U.S. military presence in Mideast A6 Iran says its troops are expelling Iraqi invaders A8 Egypt bars Israeli paper's reporters over an article A9 American labor has collected $160,000 for Polish union A12 Government/Politics Extension of child support enforcement provisions urged A14 Three Reagan Cabinet nominees breeze through Senate hearings A16 Prosecutor in upstate inquiry on corruption resigns B4 Reagan panel urges options on mass transit for handicapped B5 General Around the Nation A14 Developer of skyscrapers buys blockfront on Third Avenue B3 Unusual cold has contributed to at least three deaths in city B3 John Durniak joins Times as picture editor B4 Obituaries Irving Abramson, labor lawyer and union organizer B5 Frederick Osborn, Army general and former U.N. deputy B12 PARKING REGULATIONS Alternate-side parking regulations are suspended throughout New York City today because of the snow, the Transportation Department said. The Living Section Food For the American steak, a gilded age is fading C1 A chef and teacher starts a new life C1 Food processor battle is joined C1 Kitchen Equipment C2 60-Minute Gourmet C3 Pseudo food: It looks good enough to eat C3 Best Buys C9 Wine Talk: Brunello di Montalcino gets guarantee C13 Living Down coats cause problems in checkrooms C1 Metropolitan Diary C2 Personal Health: Raynaud's disease C10 Impact of poverty on black children cited C12 Discoveries C12 New Yorkers, etc. C12 Arts/Entertainment They nearly brought 'Frankenstein' back to life C15 National Film Critics name ''Melvin and Howard'' best film C16 Musical comedy wins first Richard Rodgers Award C16 ''Housekeeping,'' novel by Marilynne Robinson, is reviewed C18 New Federal Theater stages ''The Trial of Dr. Beck'' C18 Wildlife documentary filmed in South-West Africa on PBS C20 True Witness Ministries seeks WNYC-TV's license C20 Sports Colgate Series and Masters in tennis spotlight B6 Bucks turn back Nets, 102-86 B6 Islanders triumph over Maple Leafs, 6-3 B7 Knicks lose to Spurs, 113-108 B7 Tracy Caulkins rules the swimming world B7 Giants discharge Hawkins and Pollard, members of coaching staff B7 Survival is main topic at A.I.A.W. convention B8 B2 Oilers' manager suggests Phillips may be tampering with aides B8 Red Smith on how Landry gets the close ones B9 Features/Notes Man in the News: James Brady, choice for press secretary A15 Notes on People B4 News Analysis Steven Roberts discusses conservative coalition in House A15 Editorials/Letters/Op-Ed Editorials A18 Wrong hail to the chiefs Keeping water in mind The Iowa debate, still Topics Letters A18 James Reston: who's in charge during the transition? A19 Russell Baker: bliss among the coconuts A19 Gar Alperovitz and Jeff Faux: to avoid an 'economic Dunkirk' A19 Sue Nichterlein: educating the Spanish-speaking population A19

''I can give you me.'' - Representative Raymond F. Lederer, Democrat of Pennsylvania, describing, on a v/deotape shown at his Abscam trial, what he could give in exchange for $50,000. (B1:5.)

Henry B. Platt, the 56-year-old descendant of Charles L. Tiffany, who founded Tiffany & Company in 1837, yesterday was appointed chairman and chief executive officer of the jewelry and silverware retailer and producer. Mr. Platt, president and chief operating officer since 1974, succeeds Walter Hoving, 83 years old, who retired Jan. 1. The new chairman is a great-great-grandson of Charles Tiffany and a greatgrandson of Louis C. Tiffany, the artist and designer of Tiffany glass, much of which was displayed and sold in the six Tiffany stores. The announcement of Mr. Platt's appointment and those of other company officers was made yesterday by David W. Mitchell, chairman of Avon Products Inc., the cosmetics and fragrances producer that bought control of Tiffany in April 1979 for $104 million in stock.

West Africa - De Beers, the dominant force in the world diamond trade, is stepping up the pace of prospecting in the immense desert preserve it controls, through a wholly owned subsidiary, in this disputed territory. The subsidiary was called Consolidated Diamond Mines when Sir Ernest Oppenheimer gambled some $10 million in 1920 on German diamond concessions in the Namib Desert. Now, legally as well as colloquially, it is known only by its initials. In 1979, the last year for which figures have been published, C.D.M. accounted for 18 percent of the before-tax profits of $993 million of De Beers Consolidated Mines Ltd., or $179 million. The largest private employer in South-West Africa, C.D.M. now accounts for an estimated 40 percent of Government revenues in the territory, which is going through a painful gestation to independence.

Mark David Chapman, the 25-year-old Beatles fan accused of fatally shooting John Lennon last month, pleaded not guilty by reason of insanity yesterday morning to a charge of second-degree murder. But his court-appointed attorney said outside the courtroom that he would not contend that Mr. Chapman was unfit to stand trial. The attorney, Jonathan Marks, said he would base the defense of insanity on his client's state of mind at the time of the shooting. Later in the day, Mr. Marks requested police protection after he reported that threats had been made against him. He declined to be specific about the nature of the threats. Mr. Marks said that he had moved out of his home in Manhattan but that he had no intention of resigning as Mr. Chapman's lawyer.

Regularly scheduled helicopter service connecting Kennedy International, La Guardia and Newark International Airports and the 34th Street Heliport alongside the East River began yesterday. The service was hailed by Governor Carey as ''reaffirmation of the improving economic strength of the region.'' The operator, New York Helicopter, is a subsidiary of the 12-yearold Island Helicopter Corporation, which carried 100,000 sightseers over the metropolitan area last year. The operator hopes the new service will carry 400,000 passengers annually within five years.

Iran has responded to the latest American proposals on freeing the hostages by asking specific questions about financial matters and procedures involved in ending the crisis, Administration officials said today. The latest reply was sent here this evening from Teheran by the Algerian intermediaries. Officials said the Administration wanted to expedite its response and hoped to send it tomorrow. But the officials cautioned against assuming that a breakthrough was imminent.

Representative Raymond F. Lederer of Pennsylvania is seen taking a paper bag filled with $50,000 in cash from an Abscam undercover agent in a surreptitiously made videotape played yesterday at his trial in Federal Court in Brooklyn. ''I hope you spend it well,'' Anthony Amoroso, a Federal Bureau of Investigation agent, tells Mr. Lederer after handing him the money at the end of a 40-minute meeting in a room at the Hilton Inn near Kennedy International Airport in Queens. Earlier in the meeting, which took place on Sept. 11, 1979, and which other F,B,I, agents secretly recorded, Mr. Lederer told Mr. Amoroso and another undercover operator that he would introduce private immigration legislation to aid a rich Arab sheik whom the undercover men pretended to be representing. ''I can give you me,'' the Congressman said in describing how he could aid the sheik. The sheik did not exist, and the entire ruse was part of the Government's investigation into political corruption, which has led to convictions of four other members of the House of Representatives for taking money from the undercover people.