Fears grew that Amanda Bynes may have completely lost her mind after the former actress was seen displaying strange and erratic behaviour around New York city.

One report by gossip site TMZ said Bynes was at the city's Union Square on Friday night where onlookers said she was talking to a tree and other inanimate objects.

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Earlier that evening, she reportedly looked disheveled as she strolled on the Upper East Side, entering and exiting a shop without buying anything.

The 28-year-old actress had a bandage under her right eye, other reports said, noting that she already had the eye bandage on when she left the Los Angeles airport en route to New York.

A waitress at an airport restaurant where Bynes stopped by to eat had taken a photo of the former child star and posted it on Instagram, adding her own story about the encounter and describing Bynes as "f__king crazy" and unwell.

Brittany Anne, the waitress, said a fellow server had told her to kick out the customer at Table 141 who was putting a lot of makeup on the table.  Both did not know at first that the said customer was Amanda Bynes.

"She was like, 'Well I sat myself, one of the hostesses looked really upset and.. Blah blah blah.' She just started making s- up dude and then I was just like 'No problem girl,'" Brittany narrated, finally realizing who she was waiting on.

She said Bynes was making weird faces and talking to herself, concluding that "she's not well."

Bynes made headlines last week when she was arrested for DUI or Driving Under the Influence of a controlled substance. She also made headlines last year when she had a public meltdown on Twitter, one of the worst of a string of erratic behaviour that she had displayed through the years.

In July 2013, Bynes was brought to a hospital for psychiatric evaluation after she started a fire at a stranger's driveway.

After she was released from hospital later that yeat, she enrolled in a California Fashion Institute and was reportedly doing well --until she was arrested for DUI last week.

Bynes began her acting career as a child, later taking on teenage roles until she decided to retire from acting in 2012.

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