What was going on when I was born?

A tenant leader gave a crystal ball to the county's Rent Guidelines Board last week and even the landlords, who had been hissed and booed during a chaotic three-hour public meeting, laughed. The board had already announced that it had no information on which to base rents for the year beginning Oct. 1 because the state ran out of postage money when approval of the budget was delayed in Albany and could not send questionnaires to landlords. The decision on rents for 58,000 tenants in 18 communities in the county under the Emergency Tenant Protection Act was to be made by July 1, but the board will not be able to meet the deadline. The board is also unsure of its own makeup. Three of its members are lame ducks whose terms have expired but who have been neither reappointed nor replaced. The term of one member, Daniel J. O'Brien, expired Dec. 31, 1978; since then, Mr. O'Brien said, ''I sat, and I sat and I sat,'' but the County Board of Legislators, which must replace him, has not acted.

Britain won the war last week, but what kind of peace was in store for the Falkland Islands remained unsettled. Prime Minister Margaret Thatcher proclaimed victory for British sovereignty and ''the British way of life'' and ordered her colonial governor back to the islands. In that case, Argentine President Leopoldo Galtieri insisted, ''There will be no security or definite peace.'' But the President himself soon became a political casualty. Thousands of Argentines, humiliated by losing (and furious at being misled by military communiques), rioted below the presidential balcony, chanting ''Treason! Treason!'' The military forced out General Galtieri as army commander in chief and replaced him in the ruling junta with Gen. Cristino Nicolaides, a hard-liner. Gen. Alfredo Saint Jean, the Interior Minister, became interim President.

The big names took control of the leader boards today in the third round of the United States Open. Tom Watson, who says he wants to win this championship more than anything else, and Bill Rogers, who tied for second last year and then went on to win the British Open and the World Series of Golf, tied for the lead after three rounds, setting up what should be a splendid confrontation in Sunday's finale. Watson shot a four-under-par 68 and Rogers a 69 to stand at 212 for 54 holes of the Pebble Beach golf links. Two shots behind them were David Graham, the defender; George Burns, who tied Rogers last year; Scott Simpson, winner of one tournament in four years on the tour, and Bruce Devlin, who shared the first-day lead Thursday and held it alone Friday. And three shots back was Jack Nicklaus, licking his chops at the prospect of becoming the first man to win a fifth United States Open. Devlin is better known these days as a television commentator than a player. He missed the cut in his last tournament and he plays seldom. In eight tournaments this season, he has made the cut only four times and has won $2,932, hardly enough for expenses. After two good rounds of 70, 69, Devlin shot three bogeys today and not a single birdie.

WHEN they were infants, Barbara and Susan were adopted by the same family. They grew up as sisters in Upper Nyack, N.Y. Barbara, now Mrs. Richards, is 34 years old and lives in Valley Cottage, N.Y. She does not want to know her biological mother. ''My life couldn't be improved by finding her, by meeting this total stranger,'' she says, and a search would mean ''nothing but confusion.'' Nevertheless, a year ago, Mrs. Richards helped her sister - now Mrs. Begg - to write to an adoptee search group. The 30-year-old Mrs. Begg, who lives in Mahwah, said she ''always wanted to know'' about her birth family, and adds: ''I started searching officially last year just to find out who I looked like, what kind of history I had, why I was given up.'' The attitudes of Mrs. Richards and Mrs. Begg exemplify the deep and often emotional division that marks the debate among adoptees, adoptive parents, birth parents, lawyers and adoption agencies about whether to open adoption records.

Lebanese political leaders continued their efforts today to convince the Palestine Liberation Organization to lay down its arms in return for Lebanese and American assurances that the Israeli Army will not move into the Palestinian-Moslem stronghold in West Beirut. But despite a flurry of meetings between Philip C. Habib, the special American envoy, and President Elias Sarkis and other Lebanese politicians, there was doubt whether a political arrangement could be worked out. (An Israeli military spokesman said five Syrians were killed and three Israelis wounded in the first clash since a cease-fire eight days ago, Reuters reported. Ihe incident occurred near Karun Lake at the southern end of the Bekaa Valley.)

SABBATICAL A Romance. By John Barth. 366 pp. New York: G. P. Putnam's Sons. $14.95. WE'LL have to stick to the channel,'' John Barth wrote in his first novel, ''The Floating Opera,'' ''and let the creeks and coves go by.'' His new work explores all the creeks and coves it can, both literally and figuratively. It drifts with what one of its characters calls the narrative tide, it goes back, goes forward, stands still. It begins with a storm at sea, describes an uncanny island not to be found on any chart and records the surfacing of a hefty sea monster in Chesapeake Bay. ''Have we sailed out of James Michener,'' the narrator wonders, ''into Jules Verne?''

LAWRENCE TOWNSHIP THE offices of the Lawrence Township Planning Board sit right in the middle of the first floor of the Municipal Building. Its doors and windows bear no identifying logos or lettering, but there is no mistaking it or its work. Thick rolls of blueprints for homes and office buildings are piled at the edge of a counter. Others are atop file cabinets or stuffed into cardboard boxes. All this is more fuel for the boomlet of residential, corporate and scientific-research development that is changing the countryside of Lawrence Township and other once-sleepy farming communities around Princeton.

SCOUTING is on the rise on the Island, especially in Suffolk County, where Girl Scout registration is increasing despite national trends to the contrary. The reasons for renewed interest, according to Scout officials, include parental concern for a return to the wholesome values believed to be fostered by scouting programs as well as a growing acceptance, especially among teen-agers, of new programs. Patricia Hardy, a 16-year-old senior Girl Scout in a Kings Park troop, said: ''Two years ago, I hid my Girl Scout books from my friends. Now I sell cookies in school without being afraid of being laughed at.'' She attributed the change in attitude toward scouting to programs that are ''more visible.'' High-adventure camping trips and community projects such as a recent campaign for reserved parking stalls for the handicapped have improved the public image of Scouts.

-------------------------------------------------------------------- Margaret Croyden, the author of ''Lunatics, Lovers and Poets: The Contemporary Experimental Theater,'' writes frequently about the arts. By MARGARET CROYDEN By some standards, the theater appears to be flourishing: Broadway box office grosses are reportedly at record highs; the Dramatists Guild has a membership of over 5,000, a substantial increase over the past year, and, nationwide, thousands of stagestruck young people have been studying theater arts in college and trying out their skills on campus stages and with regional companies. On the other hand, attendance is down, ticket prices have reached levels that seem likely to discourage younger audiences, and Broadway's theaters are surviving on a diet of holdovers from previous seasons plus a scattering of newcomers and revivals. There is little to challenge or stimulate the serious theatergoer. Once, playwrights were pivotal figures in the American theater. Writers such as Clifford Odets, Eugene O'Neill, Athur Miller and Tennessee Williams dealt powerfully with important social and moral themes. Their new plays were eagerly awaited events that formed the backbone of American drama.

NEW CASTLE A remote corner of this community is decidedly suburban, but the language there is Yiddish. An 8-year-old boy politely but incredulously asks a visitor, ''You don't speak Yiddish?'' Then a younger boy on a banana-seat bicycle tears down the hill that is Tora Road, his peyos, or hair locks, flying in the wind. At the top of the hill is the Yeshiva of Nitra, the Orthodox Rabbinical College of the Yeshiva Farm Settlement. It was founded 34 years ago on 300 acres of hilly, wooded land here by a rabbi who was a Jewish resistance leader in Czechoslovakia and by a group of refugees and war orphans. Today men in yarmulkes mow down the dandelions on lawns in front of the two-family tract homes that serve as housing for married students and staff. On a sun deck, a man is praying in a long black coat, beaver hat and white shirt - the clothing of the Hasidim, the legacy of Baal Shem Tov, the 18th-century Eastern European founder of Hasidism, a mystical revivalist movement within Orthodox Judaism.

Chaotic Credit Markets After remaining at high but quite stable levels since last fall, interest rates seem about to take off again. Since the Drysdale collapse, the credit markets, which had been cautiously eyeing a projected $45 billion in Treasury financings during the third quarter, have turned skittish at the sight of new Government paper. With the economy struggling to get out of its rut, the change in attitude could not have come at a worse time. The bond investor is likely to purchase the new Treasury notes, says Edward Yardeni, chief economist at E.F. Hutton, but only at interest rates that insure a still-born recovery. And while most analysts acknowldege that recent upward movements in key short-term rates make a rise in the prime to 17 percent highly likely in the near term, that may not be the end of the increase, Mr. Yardeni says.

New York State's economy is going through a profound transition away from the brawn of steel mills, locomotive works and shipyards into the brainy world of biomedical engineering, data processing and microelectronics. The shift from traditional manufacturing is accelerating. Officials say this spring marks the first time that more than half the state's 1.5 million manufacturing workers - 51.8 percent - are in jobs directly involving high-technology goods and services. ''High technology is begetting new companies in New York almost daily,'' said George G. Dempster, Commissioner of the State Commerce Department, which is seeking to capitalize on the shift to more sophisticated products through its ''Made in New York'' advertising campaign. Mr. Dempster said the state, after a sharp drop in jobs in the early 1970's, had gained 451,000 jobs since 1975. Of new jobs, he said, 47,000 were manufacturing jobs in such fields as the production of electrical equipment and instruments. And 415,000 new jobs were in service industries and the fields of finance and insurance, he said, with a substantial but unknown percentage of these in such fields as data processing and computer operation.