About three months, ago, during the June offensive that marked the final state of Anastasio Somoza's rule, Sandinista guerrillas infilitrated Managua's industrial sector along the northern highway and used Heinz Luedeking's warehouse-office complex as a command post until the National Guard drove them out.

The Sandinistas did not give up easily. It took more than four days of constant shelling from the ground and sporadic bombing from the air before the Guard was able to dislodge the guerrillas from Luedeking's building, which his firm had completed only last March at a cost of more than $1 million.

About the only thing the rocket attacks and bombs accomplished -- besides a momentary victory for Somoza just a month before the Final Sandinista triumph -- was to destroy much of Nicaragua's industrial capacity. Luedeking estimates that it would cost Ludeca, his firm, more than $4.5 million to replace the building and inventory destroyed during the country's devastating civil war.

Where he and thousands of other Nicaraguan businessmen will find the money to rebuild their businesses, a vital necessity if Nicaragua's economy is ever to recover, remains an unanswered but increasingly urgent question.

"There is no insurance for damage due to a civl war," Luedeking said recently at his destroyed plant near the Managua airport. Until early June, Ludeca was one of Nicaragua's largest importers of agricultural and industrial machinery -- the kind of business that Alfonso Robelo, a member of the provisional junta that took over Somoza's fall, has said is vital to Nicaragua's future.

"We intend to rebuild the company if conditions permit," Luedeking said. "But so far the government has given no indication of its intentions with regard to firms like ours."

It has been estimated that private businesses such as Ludeca suffered losses of more than $600 million during the war, leaving Nicaragua' private sector virtually paralyzed and about 70 percent of the urban work force unemployed.

When the new government here talks of needing half a billion dollars in foreign assistance and loans over the next year alone, it is talking about tens of millions of dollars for companies like Luedeking's to help them rebuild their physical plants and replenish their inventories.

According to both businessessmen and leaders of the new government, such as Robelo and Finance Minister Joaquin Cuadra Chamorro, there is no other way for Nicaragua's private sector to raise the capital it needs to rebuild and restock.

The new government, which said it found only about $3 million in hard currency in the Central Bank when it came to power July 20, does not have the resources to lend reconstruction money to the private sector without massive loans and credit guarantees from abroad.

Both Robelo and Cuadra said in recent interviews that they and the new government are aware of the needs of the private sector. Both said that, despite a lack of confidence on the part of both local businessmen and some foreign observers who are suspicious of the Sandinistas' Marxist leanings, the new government is committed to a mixed economy that envisions an important and permanent role for private businesses such as Ludeca.

"I think, in general, the private sector is tremendously cautious," said Robelo, himself a businessman who is believed to be a millionaire. "But we are going to prove to them what we have said is true . . . if nothing exceptional happens."

Asked what he meant by "exceptional," Robelo replied: "I have to admit that if we don't get external help in significant quantities that could create an internal crisis that could cause us to change our current intentions. We might have to impose more internal restrictions to allow us to survive on our own resources."

Meanwhile, firms such as Ludeca are in a state of limbo.

Luedeking said that his firm owes about $2.4 million to local banks, which were nationalized shortly after the new government came to power, and to foreign financial institutions such as the Bank of America.

Like many businessmen here, Luedeking said he does not know how he will repay these debts because most of his inventory was destroyed. The only possible way, he said, is the debts are restructured on a long-term basis and new money advanced so that he can go back into business, earn profits and pay off the old and new loans.

Thus far, he said, he has been unable to find anyone at the nationalized banks who is willing to discuss his problems. As a result, Luedeking said he has been force to lay off most of the 100 employes at Ludeca.

Robelo said the new government is now working on a plan to provide some loans and other incentives for essential firms in the private sector so that they can begin rebuilding and rehiring their laid-off employes.

William Baez Sacasa, the director of INDE, an association of 700 of the country's largest businesses, said the private sector recognizes that the new government was forced to set priorities and is not in a position to do much at the moment for private businessmen not directly involved in the key agricultural sector.

As a result, Baez said, the leadership for rebuilding businesses "has to come from the private sector itself. Otherwise, we aren't going to get any money and there isn't going to be a private sector" in Nicaragua.