What was going on when I was born?

The Gener al Motors Corpo ration said today that it would reduce the prices of some cars and t rucks sold over the nexttwo months, for the most part by $750 or less . The reductions, which range from $500 to $2,000, come despite failure to obtain wage and benefit concessions from G.M.'s unionized factory workers to offset the price cuts. The company, the only domestic auto maker not currently offering financial incentives to car buyers, said the price reductions would be effective for 60 days, starting Feb.1. They would be available for about half of G.M.'s car and truck models. Roger B. Smith, chairman of G.M., said that, in the face of the worst sales slump in 21 years, there was ''a critical need in the marketplace for some kind of market stimulus.'' Earlier this month, G.M. had agreed in principle to a United Automobile Workers proposal to pass wage and benefit concessions along to consumers in the form of lower vehicle prices. Contract negotiations broke down last night, however, and a union

Officers of an organization representing peasants in E l Salvador praised the Government there this week for ''positive at titudes'' toward the troubled land-redistribution plan and for accep ting policy recommendations from the group. The group, the Union Comunal Salvadorena, which says it speaks for more than 100,000 peasants, had told Jose Napoleon Duarte, the country's President, in December that ''the failure of the agrarian reform process is an immediate and imminent danger.'' It reported the murder of more than 90 peasant leaders then and estimated that as many as 25,000 farmers had been evicted from their newly acquired land, some by right-wing gangs and some by Government security forces. Favorable Picture of Duarte Given In a four-page lett er dated Jan. 25 two off icers of the union gave a generally favorable picture of President Du arte and some other members of the civilian-military junta and sa id that a number of the peasant group's recommendations had been acce pted. While the letter did not repudiate the gloomy findings of the December report, it outlined a series of promises by Government o fficials to overcome problems arising from lethargic bureaucracy a nd widespread brutality.

The Federal appeals court here today struck down the so-called one-house veto, which allows either house of Congress to block the policies of certain Federal agencies from taking effect. In a 104-page opinion, the United States Court of Appeals for the District of Columbia said that the procedure violated several provisions of the Constitution. The court also implied that two-house vetoes, requiring a decision by both houses to block agency action, might also be unconstitutional. Congress has attached legislative veto provisions of one kind or the other to more than 200 laws, and every President since Franklin D. Roosevelt has challenged their constitutionality.

When Franklin Delano Roosevelt was President, he was a figure of fierce controversy, loved and hated by many Americans. But now, 100 years after his birth on Jan. 30, 1882, historians for the most part have come to agree that, despite flaws, he was on balance the greatest President of the 20th century. In hindsight, they say Roosevelt's faults have receded as his strengths have loomed larger. ''If anything, time seems to have confirmed the view of his greatness,'' commented Joseph P. Lash, author of the book ''Eleanor and Franklin.'' ''I am reminded of the remark Sam Rayburn made of him at a memorial service not long after Roosevelt died,'' Mr. Lash added, referring to the Texan who was Speaker of the House. ''Rayburn said, 'He saved the country twice: in the Depression and then again in World War II.' ''

New York State filed a $200 million lawsuit today against the Hooker Chemicals and Plastics Corporation, charging that it maintained toxic waste sites that led to the pollution of the Niagara River. Robert Abrams, the State Attorney General, said the suit, which was filed in State Supreme Court in Niagara County, charged that Hooker ''mishandled toxic chemicals'' at its Buffalo Avenue plant in Niagara Falls. The suit, which Mr. Abrams said was brought at the request of the state's Department of Environmental Conservation, also names the Occidental Petroleum Corporation, Hooker's parent concern, as a defendant.

A captured terrorist suspect's sudden decision to give information to interrogators four days ago provided the crucial break that enabled the Italian police to find and free Brig. Gen. James L. Dozier, according to Italian officials. The informer, who was arrested in northern Italy Monday, did not know where the general was being held, but he gave the addresses of several apartments and other locations that terrorists had been using. The police checked all the places, and the clues found in some of them led them to further hideouts and eventually to the secondfloor apartment above a grocery in Padua where the general was held, the officials said. Precision of Operation Praised In Vicenza, General Dozier praised the speed and precision of the operation by the Italian antiterrorist squad that rescued him, but he declined to disclose any details of his ordeal until after he has been questioned by Italian authorities and American officials. (Page 6.)