The balloons went up yesterday - a thousand of them - the mummers march today, and tomorrow Albert Masatti, the singing submarine shop owner, will do his thing.

Turning around an unsuccessful shopping center is no easy task.

Hiring a promotion manager to launch helium balloons and hoopla was one of the first things Robert A. Gring did when he became manager of Rockville Mall last October.

He was the fourth manager in six years for the mall, which opened in 1972 and still has vacancies. Yesterday Gring became the first manager of The Commons at Courthouse Square, the new name hung on the old mall in attempt to build the business that his predecessors had failed to capture.

A suburban renewal project for downtown Rockville, the 400,000-square-foot, enclosed shopping center with its 1,592 indoor parking spaces never fulfilled its promise of blooming into a bustling development.

Many of the merchants who lost their shops to the construction work moved elsewhere. Many of the retailers who did lease stores in the mall left, complaining of poor services and little traffic.

Yesterday Gring talked about what he's done to reverse the slide - putting planters with waterfalls in the corridors, piping sound into the echoing subterranean parking garage, and pulling new tenants into long-vacant sites.

An H.&R. Block office recently became the 38th store in the center. Old Western Chicken and Chips is opening in March, to be followed by Unisex Hairdressers and Waxie Maxie, the record chain that pulled out once and now is returning. Thats four stores in 3 1/2 months, Gring boasts.

To fill up the 15 percent of the mall that remains unleased, Gring said he is looking for a drug store, another hair stylist, camera and stereo shops, more ladies' ready-to-wear, a men's boutique and additional food shops. The goal is to be rented-up by year end.

Gring acknowledges The Commons at Courthouse Square - a name that won a trip to London for Mrs. Barbara Kaplan of Potomac - never will be as big as Montgomery Mall or White Flint.

"Let us accept what we are. We're a split between a community shopping center and a regional mall," Gring said. But the center is "a viable retailing entity in its own right," he insisted.

Although high rents were blamed for some of the shopping center's early occupancy problems, they've been raised, to the $6-to-$8-per-square-foot range. Compared to $12 a foot on Rockville Pike, that's a deal, said Gring.

With higher rents have come improved services, a coordinated advertising campaign, and amentites directed at making the shopping center more attractive to consumers.

Other hopeful harbingers are approval of a planned Rockville and Montogomery County government conplex across the street, and the scheduled arrival of Metro in 1981.