White House Communications Director David R. Gergen indicated yesterday that while the Reagan administration now believes that the "process of economic recovery" will begin later this year, a return to prosperity is a lot further off.

"To restore real health to this economy, a very sick patient, is going to take a long time," Gergen told a breakfast meeting of reporters. He said the administration believes some of the current economic problems are "deep seated" and will require rebuilding of the nation's manufacturing base.

"I think we have to distinguish between the process of recovery and what most people call prosperity," he said.

His comments were the latest in a series of efforts by senior White House officials to back away from the former rosy administration predictions of economic upsurge once Reagan's policies were put in place. The White House line generally is more cautious than that propounded in Capitol Hill testimony by Murray Weidenbaum, chairman of the Council of Economic Advisers.

The new rhetoric of lowered economic expectations by Gergen yesterday and White House Chief of Staff James A. Baker III and Deputy White House Press Secretary Larry Speakes earlier precedes release of the administration's revised midyear budget review.

Gergen indicated that that economic forecast, which has been delayed, would be "somewhat less optimistic" about the future performance of the economy than administration estimates earlier this year and would predict a "fairly modest" increase over previous estimates of the size of the budget deficit this year.