While popular 90s mainstays were meeting and greeting fans at 90s Con last weekend for a nostalgia-fueled weekend with stars like Alicia Silverstone, Kenan Thompson, Kel Mitchell, Joey Fatone, and more, former Nickelodeon superstar Amanda Bynes was absent.

Bynes was supposed to be at the gathering, which would have marked her first public appearance since her eight-year conservatorship ended in March 2022. According to Entertainment Tonight, she canceled her appearance due to an "unknown illness."

Then, news broke Monday that Bynes had been placed on a psychiatric hold after she was found wandering naked in downtown Los Angeles. 

Police responded to a call Sunday at 6:45 a.m. about a 36-year-old female standing "completely nude" on the corner of Vermont Avenue and 4th Street in Los Angeles.

THE TROUBLED AND TALENTED AMANDA BYNES

Amanda Bynes wearing a pink dress at a premirere

Amanda Bynes, seen here in 2009, was found wandering the streets of downtown Los Angeles "completely nude" and placed on a psychiatric hold for 72 hours. (Jon Kopaloff/FilmMagic)

The LAPD noted that Bynes appeared to be "suffering from mental illness," and based on statements she made, the actress was put on a psychiatric hold. Being on psychiatric hold is typically a 72-hour period, however the duration can be extended, according to the LAPD.

Stars online and in attendance at 90s Con wished Bynes well.

"Prayers for Amanda Bynes....we should be sending love her way even if its just in how we plan to help a new generation of young artists," wrote former Disney Channel star Christy Carlson Romano.

"One Tree Hill" star Sophia Bush Hughes wrote on Twitter, "I’m heartbroken for Amanda Bynes. Trauma is a lifelong beast to battle once inflicted. I hope she can get the support she needs & deserves."

At 90s Con, before anyone was aware of Bynes' situation, her fellow "All That" star Kel Mitchell told Entertainment Tonight, "I've just been praying for her. It's awesome to see she's doing better. Which is great. We're just continuing to pray for her on her journey, and it's answered prayers that she's doing a lot better." 

The incident marks the latest in a long list of difficulties the child star has faced since she debuted on television at the age of 7 in a commercial.

At 10, Bynes landed a role on Nickelodeon’s sketch series, "All That," in 1996 and was a breakout star. In 1999, she got her own spin-off sketch show, "The Amanda Show," which ran for three seasons until 2002.

Amanda Bynes in 1998

Amanda Bynes during Nickelodeon's 1998 Big Help in Los Angeles. (Getty Images)

She made her feature film debut in 2002 in "Big Fat Liar," alongside fellow child star Frankie Muniz. That same year, she landed a starring role alongside Jennie Garth on the WB sitcom "What I Like About You."

In 2006, she cemented her status as a teen comedy queen with "She’s The Man," a modern update on Shakespeare’s "Twelfth Night." The following year, she also starred in the big screen adaptation of the Broadway musical "Hairspray."

Her career slowed for a couple of years before she appeared alongside Emma Stone in 2010’s "Easy A," as a Christian mean girl. 

Amanda Bynes with Emma Stone

Amanda Bynes in a scene from "Easy A" with Emma Stone (FOX Image Collection via Getty Images)

Despite the film’s success, Bynes announced that same year she planned to go on an indefinite hiatus from acting.

Three years after that tweet, the California-born star was placed under a conservatorship. 

After a DUI arrest, a probation sentencing, a marijuana possession charge and a string of other public incidents, including inappropriate tweets and allegations she started a fire in a driveway, Bynes was placed under a conservatorship in 2013 run by her mother, Lynn Bynes. 

Amanda Bynes red carpet

Amanda Bynes said she was retiring from acting in 2010. (Getty Images)

SOURCE: AMANDA BYNES 'DOING WELL' UNDER PSYCHIATRIC HOLD

Bynes continued to draw attention for court appearances and tweets, including one accusing her father of sexual abuse. In 2016, Bynes’ mother filed to continue the conservatorship over the actress.

Her life seemed to settle eventually. In 2018, she was chosen by Paper Magazine for the third "Break the Internet" cover feature. (Kim Kardashian was the outlet’s first "Break the Internet" subject.)

In the interview, Bynes admitted to smoking marijuana as a teen, which lead her to experiment with other drugs, including molly, ecstasy and cocaine. 

But she said it was Adderall that led her to walk off the set of 2010’s "Hall Pass," one the first hints at Bynes' decline. 

Amanda Bynes mugshot

In April 2012, the former Nickelodeon star was arrested for DUI after allegedly sideswiping a police cruiser.  (Los Angeles County Sheriff's Department)

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"When I was doing ‘Hall Pass,’ I remember being in the trailer and I used to chew the Adderall tablets because I thought they made me [more] high [that way]," she told Paper. "I remember chewing on a bunch of them and literally being scatterbrained and not being able to focus on my lines or memorize them for that matter."

She also revealed that she struggled with her appearance at the time, which prompted her to quit. 

Bynes revealed that seeing a screening of "Easy A" while high on marijuana fueled her insecurity.

"I saw it, and I was convinced that I should never be on camera again, and I officially retired on Twitter, which was, you know, also stupid," she recalled. "If I was going to retire [the right way], I should've done it in a press statement — but I did it on Twitter. Real classy! But, you know, I was high and I was like, 'You know what? I am so over this' so I just did it. But it was really foolish, and I see that now. I was young and stupid."

Amanda Bynes in a blue wig and sunglasses outside of court.

Amanda Bynes made several court appearances over the years, including an infamous one in a blue wig in 2013 at the Manhattan Criminal Court.  (Raymond Hall/FilmMagic)

The retirement from acting led her to a "seedier crowd" and self-isolation, including spending a lot of time on social media, which she said she regretted.

"I'm really ashamed and embarrassed with the things I said. I can't turn back time, but if I could, I would. And I'm so sorry to whoever I hurt and whoever I lied about because it truly eats away at me. It makes me feel so horrible and sick to my stomach and sad," Bynes said. "Everything I worked my whole life to achieve, I kind of ruined it all through Twitter." But, she adds, "it's definitely not Twitter's fault — it's my own fault."

Bynes revealed at the time that she was four years sober with the help of her parents.

Amanda Bynes in a white shirt with her parents Rick and Lynn Bynes

Amanda Bynes (center) with parents Rick and Lynn Bynes in 2004. Bynes was eventually placed under a conservatorship by her mom. (Mark Sullivan/WireImage)

"Those days of experimenting [with substances] are long over. I'm not sad about it, and I don't miss it because I really feel ashamed of how those substances made me act. When I was off of them, I was completely back to normal and immediately realized what I had done — it was like an alien had literally invaded my body. That is such a strange feeling," she said.

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She didn’t address the conservatorship in the interview and didn’t specify any mental health diagnosis, calling people reacting to her behavior online as "armchair psychiatrists."

"It definitely isn't fun when people diagnose you with what they think you are," said Bynes, now 36. "That was always really bothersome to me. If you deny anything and tell them what it actually is, they don't believe you. Truly, for me, [my behavior] was drug-induced, and whenever I got off of [drugs], I was always back to normal.

"I know that my behavior was so strange that people were just trying to grasp at straws for what was wrong."

Bynes shared that she was hoping to return to acting and was also enrolled at the Fashion Institute of Design & Merchandising. She later graduated in 2019 with a bachelor’s degree.

During that time, Bynes was also in an on again-off again relationship with Paul Michael.

Amanda Bynes in a white shirt, sunglasses, talking on a phone at LAX

Amanda Bynes in 2014. She had an on again-off again relationship with Paul Michael before finally calling it quits in 2022. (GVK/Bauer-Griffin/GC Images)

The pair began dating in 2019 during the actress’s time in a sober living facility and became engaged in 2020. Weeks after the announcement, they split but reunited shortly after. 

In April 2022, Bynes accused Michael of relapsing and kicked him out of her home. He reportedly called the police, and Bynes later apologized for the accusation. Shortly after the incident, the pair reportedly split for good.

Bynes' mother and father routinely renewed her conservatorship since 2013.

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In 2022, Bynes filed to have it terminated and succeeded in March, with the judge ruling it was "no longer required" in a tentative ruling.

"Words can't even describe how I feel. Wonderful news. Following today's decision by the judge to terminate my conservatorship, I would like to thank my fans for their love and well wishes during this time. I would also like to thank my lawyer and my parents for their support over the last nine years," Bynes said in a statement in March 2022.

The move seemed to be a positive one, celebrated not only by Bynes, but her mother too.

"Lynn is so proud of Amanda and the progress she has made and looks forward to having a mother-daughter relationship with Amanda outside of the conservatorship," Tamar Arminak told Fox News Digital on behalf of Bynes' mom, Lynn.

Amanda Bynes with her mom Lynn on a red carpet

Amanda Bynes and her mom in 2004. (Bowers/Getty Images)

Bynes' attorney David Esquibias, told Fox News Digital that, since the start of the conservatorship, the actress has worked "side by side" with her parents.

"Although she did not necessarily agree to the imposition of the conservatorship when it began, she certainly did not resist," he continued. 

"Although difficult at times, Amanda understood the conservatorship to be helpful, and in her best interest. During the conservatorship, Amanda’s parents set guidelines for Amanda to live within, which she did successfully. The termination of the conservatorship is the product of years of collaboration between Amanda and her parents. I am proud of Amanda and her accomplishments."

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Fox News Digital has reached out to Bynes’ mother and attorney following her recent psychiatric hold but has not received a response yet.

Amanda Bynes in a black off the shoulder dress

Amanda Bynes was supposed to attend 90s Con over the weekend but dropped out due to an "undisclosed illness" according to Entertainment Tonight. (Jamie McCarthy/WireImage)

In January, Bynes told People she was looking forward to 90s Con and was "really excited" to reunite with her "All That" co-stars.

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Danny Tamberelli, a fellow Nickelodeon alum with a starring role on "The Adventures of Pete & Pete," told People at the event over the weekend he was excited for the reunion too.

"I wasn't in contact with her in the last few days. Just sent some well wishes and excitement to see her over the weekend," he said, adding, "I care about her, and she was always a third sister to me."