Samuel K. Doe, who last year proclaimed himself winner of a disputed election and who this year is presiding over an economy on the brink of collapse, has launched a campaign to persuade the world's bankers that he has been transformed into a prudent manager of money.

The "new" Doe -- whose titles since 1980 include Master Sergeant Doe, General Doe, Commander-in-Chief Dr. Doe, and now His Excellency the President Dr. Doe -- has admitted that his policy failures have pushed Liberia into a precarious economic position.

One knowledgeable analyst here characterized that position as "at death's door."

In a remarkably self-critical speech, Doe said in May that a "major source of our problems" is that Liberia's government spends more than it earns and that "financial discipline continues to elude us."

The speech acknowledged that Doe's government routinely had spent money without accounting for where it went, and that his ministries had subsidized their profligacy by dipping into the earnings of public corporations. He asked the International Monetary Fund, the World Bank and the European Community to send money managers to Liberia to supervise tax collection and government spending.

This spring, Doe appointed a new minister of finance, Robert Tubman, who is a graduate of Harvard Law School and the London School of Economics and who has held several high-level positions in international economic agencies. Tubman has been dispatched to Washington and Europe to spread word of the new economic orthodoxy.

To top off the recent change in his image, Doe last month freed all of those who had been charged with complicity following an abortive coup last Nov. 12.

He also called for national reconciliation among his political opponents. The bloody coup attempt, in which the U.S. government estimates 400 people were killed, followed by two weeks Doe's announcement that he had won an election that independent observers here said he had lost by a wide margin.

Behind Doe's professed economic conversion and his apparent willingness to forgive his political enemies lies what Doe says is "the risk of further economic depression, dislocation and possible collapse."

The U.S. government also is pushing the 34-year-old president. Washington has had a special relationship with Liberia since the west African country was founded in 1847 by freed American slaves.

Since Doe seized power in 1980, after an Army coup in which president William R. Tolbert Jr. and 13 members of his government were killed, that relationship has become even more special, with the U.S. funding up to one-third of the Liberian government's operations.

In Doe's first five years in power, U.S. assistance to Liberia increased six-fold, reaching $86 million for last year. Over the period, this nation of about 2 million people received more aid per capita than any other in sub-Saharan Africa.

A large reason for the American generosity was Washington's stated desire to smooth Liberia's transition from military to elective government. American diplomats here were surprised and angered when Doe, after leading them to believe he would return to his barracks, decided to run for Liberia's civilian presidency.

Widespread election irregularities last October -- including the discovery of thousands of burned ballots and arbitrary changes in vote-counting procedures that Doe himself had approved before the election -- further sullied Doe's image in Washington. Congress demanded, in a nonbinding resolution, suspension of military aid to Liberia. Chester A. Crocker, the assistant secretary of state for African affairs, acknowledged that "serious questions" remained about the election count.

But the Reagan administration, while reducing military and economic aid requests for Liberia this year, has refused to give up on Doe. Instead, according to informed sources here, it has pressed for fiscal responsibility. His transformation followed two high-level visits by U.S. officials, one of whom was Crocker.

Analysts close to the government say Doe was told to get his economic house in order, replace corrupt subordinates, sell off unprofitable state enterprises, call in outside economic advice, release political prisoners and tolerate political opposition or face loss of U.S. economic aid.

Without the U.S. money, analysts say that Doe's government faces the loss of what little foreign investment remains. Liberia in the past two years has become one of the "basket case" economies of Africa. Interest on its $1.2 billion foreign debt exceeds annual government revenues.

Liberia's failure to pay its debts has led the IMF, the World Bank and the African Development Bank to suspend all of their programs here. The government frequently has fallen three or four months behind on its payroll. Prices for the country's major exchange earners, iron ore and rubber, are in a slump.

Liberia uses U.S. currency as its own. But that arrangement is vulnerable to collapse, economic analysts say. To pay salaries and smooth out other monetary problems, Doe's government has flooded the country with $60 million of its own "Doe dollar" coins in the past year.

In the political sphere, Doe agreed to participate in reconciliation talks with opposition parties under the auspices of the Liberian Council of Churches. It was a move advertised by the government as an example of Doe's desire for national unity.

But when the Council of Churches proposed a new election for some members of the Liberian legislature, which Doe controls, Doe's supporters called the proposal "unconstitutional" and backed out of further negotiations.

In a major speech on freedom of the press in Liberia, Doe's new minister of information, S. Momoluh Getaweh, warned journalists that "there should be no perverse criticism of the government."

Accordingly, there was no critical reaction in Monrovia's newspapers to a nationwide announcement Thursday that a new photograph of Doe as Liberia's elected president is now available for purchase at the ministry of information.

The color photograph, which shows President Dr. Doe in a dark-blue double-breasted suit, must be purchased by all Liberian businesses to replace a similar photograph of Commander-in-Chief Dr. Doe. A gold framed photograph sells for $1.60, an unframed one for $1.10.