What was going on when I was born?

In a move aimed at getting the money it needs to meet a debt payment due Friday, the Brazilian Government has agreed to curb the so-called indexation of its economy, a once-hailed innovation that protected workers' salaries against large increases in the cost of living. The Government's action, taken Wednesday night, took the form of a new regulation restricting salary increases in the next two years to a level 20 percent below the official cost of living figure. Under indexation, salaries had been automatically increased every six months to keep up with inflation. Indexation, a concept first popularized by the Brazilians in the 1970's and since adopted by other countries, ties not only wages but also taxes, rents and a range of other consumer costs to movements in the cost of living.

To the merchants along Avenue D in Brooklyn the empty storefront is a sore spot, as painful and unsightly as the space left by a newly missing tooth. ''Look, this is what happened to business when the bank closed,'' said Allen Spiro, the owner of a floor covering store in the East Flatbush neighborhood, as he pointed to the empty parking spaces up and down his block. Asserting that the closing last month was a setback in the neighborhood's decade-long struggle against deterioration, Mr. Spiro said: ''Since Citibank left, there have been less people on the street. Business has just dropped off. That bank was an anchor for this commercial strip.''

The leader of the Republican majority in the State Senate today ordered the Senate to reconvene July 25 to retaliate against Governor Cuomo for ousting a Republican from the State Commission of Investigation. ''The Republican Party of the state -the Republican majority of the Senate - will not be treated as a doormat by any governor,'' the leader, Warren M. Anderson, said in a statement. Senator Anderson said Governor Cuomo had broken an agreement made with former Gov. Hugh L. Carey to get approval from Republicans for certain nominees to the commission. But Mr. Cuomo said today that he ''was aware of no such agreement.''

MANY great composers have found inspiration in nature. It is said that Beethoven used to thrash through the woods, tinkering with nascent melodies along the way. The French composer Olivier Messiaen rises at dawn every day to listen to morning birdsong. Natural surroundings can provide an excellent ambience for experiencing music of all kinds. Fortunately for New Yorkers who would like to test this proposition for themselves there are plenty of places in and around the city, from elegant estates to city parks, where live outdoor music can be heard this weekend. There's Beethoven on the Hudson, Brazilian music in Manhattan, a tribute to Brooklyn's own Aaron Copland in Prospect Park and up at Tanglewood, there's Brahms. The atmosphere at these events varies as widely as the music. At most of these, a folding chair, a well-stocked picnic hamper, a bottle of wine are welcomed on the grounds at least; if there is any doubt, it's a good idea to call ahead. A sweater or a blanket, even on the mildest of evenings, is always advisable.

The House of Representatives, with the nearly unanimous support of the Republican minority, today approved a scaled-down version of the trade portion of President Reagan's 1982 Caribbean Basin Initiative. The bill, the second part of the Reagan proposal to be approved, would allow a variety of goods from the region to be imported dutyfree. An initial part of the package, $350 million in aid, was approved by Congress last year. A third part, tax proposals designed to stimulate investment in the area, have not been considered.

For five years, Marty Woodle has carried a small loose-leaf notebook, scribbling down ideas as he went about his job at the Brookhaven National Laboratory. Today, he crossed out almost everything in the notebook. ''It's all moot now,'' said Mr. Woodle, a 42-year-old engineer who supervised four technicians at the lab. ''Hopefully I'll be able to apply what I learned here to some other project, but there's no guarantee. I'm in limbo. That's frustrating, and that's hard to take.''

The Chrysler Corporation's announcement that it will repay within weeks the remaining $800 million of Government-guaranteed loans that saved it from bankruptcy just a few years ago is a dramatic indication, as it was intended to be, of the sharp reversal of the company's fortunes. It is hard to overstate the magnitude of the turnaround. As recently as 1980, Chrysler lost $1.7 billion and, at times, was just hours from failure. Now it has $1.5 billion in cash on hand and is expected to earn a profit of about $900 million this year.

International New fighting in Nicaragua is being pressed by rebels led by Eden Pastora Gomez with newly acquired aid from other Latin American countries, according to leaders of Nicaraguan exile groups in Costa Rica. Alfonso Robelo Callejas, an exiled former member of the ruling Sandinista junta, said the rebels were planning ''a few surprises'' next week for the fourth anniversary of the overthrow of Anastasio Somoza Debayle. (Page A1, Col. 1.) Brazil began a new austerity program in an effort to secure a resumption of loan payments from the International Monetary Fund. The Government has instituted a law restricting pay increases across the country in the next two years to a level 20 percent below the cost of living figure. (A1:4.)

The International Business Machines Corporation, citing a sharp rise in computer equipment sales and continuing improvement in operating margins, reported yesterday that earnings for the second quarter soared 24.1 percent, to $1.34 billion, one of its largest quarterly profits ever. The profit, amounting to $2.22 a share, was better than many analysts had expected, and some said it was indicative of a record year for the huge company. In last year's second quarter the world's largest maker of computers and information-processing equipment and systems earned $1.08 billion, or $1.81 a share. Revenue of the Armonk, N.Y., company in the latest three months climbed 19.1 percent, to $9.59 billion, from $8.05 billion.

In 1981, Nadja Salerno-Sonnenberg won the Walter W. Naumburg International Violin Competition. Since then, she has performed at Carnegie and Alice Tully Halls. At Avery Fisher Hall tonight and tomorrow night at 8, she and the pianist Emanuel Ax will perform with the Mostly Mozart Festival orchestra conducted by Gerard Schwarz. The program consists of two Mozart pieces, the Piano Concerto No. 21 in C (K. 467) and the Violin Concerto No. 3 in G (K. 216). Also on the program are Bach's Sinfonia in D and Mendelssohn's Symphony No. 4 in A (Op. 90). There are still tickets at $8 for the second and third tier. As is the custom, a free preconcert recital by one of the performers - which one has not yet been revealed - will be given at Fisher Hall from 7 to 7:30 P.M. Box office: 874-2424.

The assets of the nation's money market mutual funds rose $252 million last week, to $165.53 billion, for the first weekly gain since last Dec. 1, the Investment Company Institute reported yesterday. The rise followed 31 consecutive weekly declines in which a total of $66.18 billion left the mutual funds. Much of the money flowed into the money market deposit accounts that banks and savings institutions were authorized to begin offering in mid-December. And some of it, analysts have said, was invested in the stock market to profit from the rally that began last summer.

The forces of Eden Pastora Gomez, bolstered by newly acquired aid from within Latin America, are resuming their fight against his former Sandinista comrades in Nicaragua, according to leaders of Nicaraguan exile groups here. ''We are planning a few surprises for the celebration next week,'' Alfonso Robelo Callejas, an exiled former member of the ruling Sandinista junta, said in a interview here Wednesday. Mr. Robelo, who is now allied with Mr. Pastora's Costa Rican-based armed opposition, was referring to the commemoration July 19 of the fourth anniversary of the overthrow of Gen. Anastasio Somoza Debayle. Mr. Robelo said Mr. Pastora never intended to give up the battle when he said last month that he was temporarily withdrawing from the field. He said Mr. Pastora only meant to postpone the fighting until aid could be found after a rush of unequipped volunteers bankrupted the force. That aid, Mr. Robelo added, is now coming from sources in Latin America that he did not name. ''We were not abandoning the fighting,'' he said. ''We never wanted to give that image. We were broke.'' At Mr. Pastora's headquarters here, a spokesman for the guerrilla force confirmed that the fighting had resumed in Nicaragua after a short pause.