Amanda Bynes arrested on suspicion of DUI, dad unaware of her whereabouts

It seems Amanda Bynes may be struggling once again.

The actress, who had a very public breakdown and has since been doing better with the help of her parents, was arrested on Sunday after police determined she was driving under the influence, authorities said.

Bynes' father told X17 that he learned of his daughter's arrest through the press and that he and his wife had not heard from Bynes outside of the occasional "greeting" since their conservatorship ended earlier this month.

Bynes, 28, was stopped by a California Highway Patrol officer after she stopped in the middle of an intersection in the Van Nuys neighborhood of Los Angeles around 4 a.m. on Sunday.  Police determined the former child star was under the influence of an unidentified drug after being evaluated at a nearby police station, the CHP said in a statement.

TMZ reported that Bynes had taken Adderall before getting behind the wheel. According to the gossip site, she was prescribed the drug by a doctor.

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The release states that Bynes, who has had a series of driving-related arrests, was cooperative but appeared disheveled when she was taken into custody.

Bynes was released hours later after posting $15,000 bail. A phone message left by The Associated Press for her criminal defense attorney, Richard Hutton, was not immediately returned.

The one-time actress remains on probation for a 2012 case filed after she clipped a Los Angeles County sheriff's patrol car and was arrested for driving under the influence. Bynes pleaded no contest to alcohol-related reckless driving in February.

In June, a New York judge dismissed a criminal case filed after Bynes was accused of throwing a bong out of her 36th-floor apartment. The case was dismissed after Bynes complied with orders to receive counseling and stay out of trouble.

Last year, Bynes resolved a misdemeanor hit-and-run case in Los Angeles after entering a civil settlement with other drivers.

She received psychiatric treatment last year after authorities said she set a small fire in the driveway of a home in Thousand Oaks, Calif. She later entered a rehab facility and was released after a lengthy stay. Her parents had been caring for her until their conservatorship ended, and she has been spotted taking fashion design courses at the Fashion Institute of Design & Merchandising in San Diego.

Once out of rehab, Bynes deleted her controversial tweets from last year, which included some vulgar messages she wrote about rapper Drake and nearly nude pictures.

In April 2013, the former actress revealed she had shaved her head, but her recent photos show her sporting long, blond locks once again.

Bynes first began acting in commercials at the age of 7 and was thrust into the limelight when she later became one of the stars of Nickelodeon’s comedy show “All That.” She then starred in Nickelodeon’s “The Amanda Show” from 1999-2002. Since then, her acting career has waned, and her last major role was in 2010’s “Easy A,”  which starred Emma Stone. Before that she appeared in films like “What a Girl Wants” and “Hairspray.”

She has publicly stated that she has retired from acting.

The Associated Press contributed to this report.