He was never interviewed and never testified, but fittingly President Reagan has become the last public witness of the Iran-contra proceedings. It is doubtful, however, given the many questions he left unanswered, that last night's nationally telecast speech will be the last word on the affair -- or will entirely satisfy the public and his critics.

Reagan's account of his role was as inconclusive as those of many who appeared before the Iran-contra congressional investigating committees during the last three months.

His speech was not a mea culpa for what had happened and not a full explanation either. His focus, as expected, was on the future, not the past; on learning general lessons, not examining specifics of why things went wrong -- such as who in his administration was responsible and what should be done to prevent similar problems stemming from secret White House policies.

He offered no assessment on whether the congressional hearings had been useful or whether his former aides, Lt. Col. Oliver L. North and Rear Adm. John M. Poindexter, deserve punishment -- or pardons.

When the television cameras focused on Reagan seated behind his Oval Office desk last night, they were also portraying the last act of a real-life television drama that had been played out since spring in the homes of millions of Americans. Those watching had experienced numerous emotional moments during the televised congressional hearings -- the boyish earnestness of North, the decorated Marine whose admission of deceit in the service of superiors attracted an outpouring of support; the forgetful manner, and barely suppressed resentment expressed by Poindexter; the refreshingly blunt candor of Secretary of State George P. Shultz, battling for his honor. But all these only set the stage for Reagan's televised account last night.

The cumulative testimony of the hearings had damaged Reagan badly in the public mind, at least as measured in opinion polls. They reported that as many as 60 percent of the people did not believe the president had been telling the truth about the Iran-contra affair.

With all that backdrop and with all the obvious high political stakes, the president appeared unusually subdued when he spoke last night. There was no fire, no passion, almost no emotion in the way he delivered his text. His manner belied his words. He stumbled slightly at times over certain passages, and the fact that he was reading from a TelePrompTer seemed more evident than usual from such a polished television performer. He also seemed to race through his remarks more than usual, finishing his entire commentary on the Iran-contra affair, for instance, in just seven minutes.

Beyond his general comments -- a recounting of personnel changes already made, new procedures on congressional consultation and notification of covert operations already announced, and brief expressions of hope that trust will be restored between the White House and Congress -- Reagan provided little new about the secret inner workings of his presidency that were revealed by the Iran-contra hearings.

Despite earlier statements that he was only awaiting the end of the hearings to shout out his reactions, he was clearly intent on putting it all behind him as quickly as possible.

In effect, the president last night rested his case with the American public by saying "I respect you too much to make excuses" and adding that "there's nothing I can say that will make the situation right."

By choosing to ignore so many questions that only he can answer, the president added another element of high-risk strategy to that already pursued throughout the long Iran-contra affair.

In 250 hours of public testimony from 29 witnesses spread over three months, the Iran-contra hearings added a wealth of damaging evidence to the story of Reagan administration secret policies gone awry. The hearings failed to resolve, however, questions about the attitudes that had produced these problems and specifically what part Reagan played in developing them -- and what he thought about them.

Here, among the many unanswered questions, are some of the key ones:

What led Reagan's aides to believe they were following his wishes? What, or who, created the climate in the White House that permitted secret activities to flourish? What made Poindexter think that the president, if asked, would have approved the secret scheme of diverting Iran arms sales profits to aid the Nicaraguan contras? Does the president now believe he knows the full story of what happened, who else was responsible, or what other possible secret activities might have been undertaken by his aides? How does he feel about the record of officials lying and misleading Congress and the public as documented in the hearings?

Does he acknowledge, contrary to his statement toward the end of the hearings, that crimes might have been committed? Is he satisfied that his administration, especially the attorney general, carried out its investigation properly and effectively?

Finally, he left people uncertain about one most important aspect of the affair: what he himself feels about it and how important he believes it to have been.

"At times," he said, "I've been mad as a hornet." But he didn't appear upset on the television screen last night. His general feelings seemed better expressed when he characterized the affair as "the Iran-contra mess."