California Gov. Edmund G. (Jerry) Brown Jr. resumes his quest for the presidency Saturday with his campaign newly damaged by events over which he had little control.

On a single day last week Brown learned that his scheduled Iowa debate with President Carter and Sen. Edward M. Kennedy had been canceled and that the California Supreme Court had ruled in favor of Republician Lt. Gov. Mike Curb in a dispute about who has gubernatorial authority when Brown is out of state.

These setbacks came after a month in which Brown's fund-raising efforts, despite some improvements, continued to lag below expectations. It was also a month in which Brown backed the losing candidate in the San Francisco mayoralty race and found an old friend, the United Farm Workers' union, repudiating a published account that it was about to endorse him for president.

Carter pulling out of the Iowa debate, which had been scheduled for national television coverage and was subsequently canceled, was by far the biggest blow.

"The debate would have helped make this a three-person race, it would have been a boost to us," said Brown campaign manager Tom Quinn. "Without that we're just going to have to keep going as best we can and to the extent that the clock on the campaign is set back six or seven weeks, we have to hang in longer."

Brown, in a December interview in Sacramento, said that the debate was "Very important" to him and that he expected to do well in it.

Throughout his political career Brown has, in fact, done well on televsion, and he more than held his own in 1974 and 1978 debate encounters in gubernatorial races.

Now, he must rely on solo appearances and the hope that sometime, somewhere, Carter will find it necessary or politically desirable -- to appear face-to-face with his opponents.

Quinn is mildly optimistic about an upward trend in fund-raising, which he said produced about $400,000 in December. He attributes the gain to some slide in liberal support for Kennedy.

Even so, the Brown fund-raising effort has produced about half of what Brown's strategists were estimating four months ago. A particular disappointment was a Dec. 21 rock concert in San Diego featuring the Eagles, Chicago and Brown's friend, singer Linda Ronstadt, which failed to fill the 14,000-seat capacity San Diego Sports Arena.

Ronstadt and friends drew a paid attendance of 9.654, including 8,500 who met the stringent rules of the Federal Election Commission, which required a pre-sold ticket that included the purchaser's nane and address as a condition for matching funds.

Despite claims by some aides that Brown made $40,000 on the concert, the actual net probably was closer to $175,000.

Overall, says Quinn, the Brown campaign has raised about $1.1 million, including $500,000 that qualifies for matching funds. The campaign has $250,000 in the bank. With federal matching money, Brown, should be able to compete at least in the Iowa caucuses and the first tier of primaries in New England.

What will happen after that, as both Brown and his aides have expressed it, is up to events. Quinn acknowledged that he saw no immediate opening for Brown but expressed the view that one of the two leading candidates, probably Kennedy, would no longer be seen as a serious contender after the early primaries. In that circumstance, he said, Brown might emerge as an alternative to Carter.

Brown will swallow his disappointment at the canceled debate and campaign strenuously in Iowa for three days beginning Saturday. He also will campaign in Chicago and Milwaukee before returning to California.

While Brown is away, control of the executive branch will pass to Curb under a ruling made Dec. 27 by the state Supreme Court, which held that the lieutenant governor may exercise the powers of Brown's office while the governor is out of state.

In acting, the court reaffirmed the traditional role of lieutenant governor as defined in the California Constitution despite the argument of Brown's legal affairs secretary, J. Anthony Kline, that modern communications enabled the governor effectively to perform his role even when he is not in California. Brown was out of state on 24 occasions during 1979 for a total of 81 days.

The court resolution of the issue was brought about by a judicial appointment Curb made during one of these Brown absences. The ruling did not change anything since the court found that Brown had the authority to withdraw Curb's appointment, as he did, since it had not been confirmed by the Commission on Judicial Appointments.

But the court said also that the state's constitution placed upon the lieutenant governor "complete, albeit temporary, responsibility for the supreme executive power of the state." This means that Curb can sign or veto bills or remove members of the Brown cabinet, who could then be reappointed but would require confirmation by the not-always-friendly State Senate.

Both Brown and his executive assistant, Gray Davis, have tried to minimize the impact of the ruling. However, there is a brief on both sides of the political aisle in Sacramento that Brown will have to work more closely with the legislative leadership than he has in the past or risk being embarrassed when he is away campaigning.