One year after Laurie Hendrick started living in a private residential community for the retarded in West Virginia, her father says, she has stopped tearing at her face, attacking her friends and family and screaming and cursing by the hour. "I'm nice all the time now," she says.

But in May Laurie turned 21 - the age at which the Montgomery County Board of Education is no longer required to pay for her education.

She faces the prospect of having to return to her home in Wheaton, leaving what her father, Philip Hendrick, says is the first program to deal effectively with both her behavior problems and her mental retardation.

State officials concede there are no facilities in Maryland for retarded people who are mentally ill. Hendrick's father can find no state agency willing to assume the cost of her out-of-state placement.

Hendrick said he cannot afford the approximately $12,000-a-year cost of keeping Laurie at Concord, a community of 30 mentally retarded adults on 170 acres of farmland in Yellow Springs, W. Va., where an attempt is made to deal with emotional problems.

Hendrick, a widower with two teen-age dauthers, says he makes about $22,000 a year as an employe of the Montgomery County government.

Yesterday Hendrick called a press conference to announce plans to file suit to force the state of Maryland to keep his daughter at the West Virginia facility rather than return her to Maryland where he claims she was the victim for 16 years of what one mental retardation expert has called "agency bounce."

Laurie's parents discovered when she was 3 that she suffered from PKU, a condition that causes irreversible brain damage. With an IQ of 61, she is classed as only mildly retarded but also has been diagnosed as a paranoid schizophrenic.

Hendrick said various federal, state and local agencies have been saying they lack jurisdiction, they have no money or their policy doesn't permit paying for adults in out-of-starte residences.

With the help of several politicians and advocacy groups, Hendrick got an assurance from the office of Gov. Harry Hughes that a decision on whether the state can help Laurie remain in West Virginia would be made by June 1. That date has been pushed back twice, he said, and the state now says it will decide on June 30, the day Laurie's funding from Montgomery County runs out.

Ben McCloud of the Maryland Mental Retardation Administration said the problem with existing state institutions is that they are firmly rooted in one discipline or another. Mental retardation facilities have no psychiatrists to deal with emotional problems, and mental health institutions have no teachers of vocational and personal hygiene skills.

Acknowledging the problem, Charles Buck, the newly appointed secertary of Maryland's Department of Health and Mental Hygiene last week directed the retardation agency to plan facilities for the mentally retarded with emotional problems.

But, added deputy secretary Leonard Albert, "It's a question of money."

"We are trying to develop the facilities," said Richard Dunne, of the governor's office of Coordination of Services for the Handicapped. "This kind of case tears my guts out."

Whatever the future brings for others like Laurie, her own case is far from Resolved. Dunne said the state has to make sure in her case that Concord is appropriate for her.

"If she left here now, it would really upset her," responded Rolf Mielzarek, the director of Concord. "A lot of [Laurie's] good behavior is all coming together, but it hasn't been entrenched. It's very fragile. Her old behavior could return very easily."

Hendrick said his wife "is thought to have committed suicide" four years ago and he believes her death was partially a result of the pressures of having a child that no one knew how to treat. "She had reached the point where she was emotionally drained - she had spread herself too thin, always working on eight different groups for the retarded."

Some experts estimate that there are a million mentally retarded persons in the United States in need of mental health services.

Charles Leight of the state retardation, administration said his agency is reluctant to provide the money to keep Laurie at Concord because "we don't want to set a precedent of funding everybody who may not fit into our agency."

He added that it is the agency's unwritten policy not to fund adults in out-of-state residences. "Economically, we can do it just as cheaply in Maryland . . . And a lot of families have suggested we bring them back closer for visitation."

It is that policy that Hendrick said he will ask a court to declare "in excess of statutory authority."

If the funding is cut off, he said, "Laurie will have to be on the streets. If she regressed, started her violent outburst again, I couldn't have her live with me here." CAPTION: Picture, Laurie Hendrick, living in a home for retarded in West Virginia, says, "I'm nice all the time now."