A Long Island dad got so drunk that he left his 3-year-old daughter in a Subway sandwich shop in Harlem during a Saturday night binge, and didn’t realize it until the next morning — when the child’s mother asked him where their little girl was, cops and witnesses said.

Stanley Frederique, 34, a nurse’s assistant from Elmont, abandoned his daughter, Nataleigh, in the fast-food eatery on Saint Nicholas Avenue around 11:30 p.m., police said.

The little girl, wearing a blue polka-dot dress and pink leggings, was spotted on surveillance video happily skipping on the sidewalk outside the shop holding her father’s hand just moments before he brought her inside, bought her a turkey sub — and headed for the door.

Witnesses said the panicked child tried to run after him, but he screamed at her to stay.

“[She yelled] ‘Daddy! Daddy!’ and he came back and opened the door and yelled, ‘Sit down! I’ll be back!’ ” said Mohammed Rahman, 37.

“He appeared drunk. He was abnormally rude,’’ Rahman said. “The little girl said nothing, and he just yelled at her, yelling, ‘Go inside! Sit down! I’ll come back!’ She was a very nice little girl. She was very happy. She had her sandwich.’’

You guys don’t know what’s going on in my life. I got problems, OK? I’m sick. - Stanley Frederique

After about 20 minutes, the youngster caught the attention of a customer, Michaela Warnsley of Harlem — who happens to be a child welfare worker.

“I asked her, ‘Where’s your mommy and daddy?’ and she pointed to the [street] corner,’’ Warnsley told The Post.

Warnsley said she walked the child to a police station house.

“They decided they were going to take her to the hospital,” Warnsley said. “It was a traumatic experience for her.”

Her father realized what he’d done only after he called the child’s mother, Marleana Neeper, from a cab at around 7:30 a.m., law enforcement sources said.

As he was telling her he was on his way home, she asked where their daughter was — and he realized he had no idea and started freaking out, the sources said.

Mohammed Wasay, 47, who owns the laundry where Neeper works, said the mom “could barely breathe.”

“Marleana had no clue her daughter was missing,” said Wasay, who spoke with Neeper afterward.

The cabby hailed a traffic cop, and they took Frederique to the 84th Precinct in downtown Brooklyn, where he blubbered to police that he had lost his kid, sources said. Cops charged him with child abandonment and reckless endangerment.

As cops hauled the dad off to court, he made excuses for leaving his little girl.

“You guys don’t know what’s going on in my life. I got problems, OK?” he said. “I’m sick.”

Nataleigh arrived home in her mother’s arms Sunday evening. Her dopey dad was taken to Bellevue Hospital Center.

Frederique has been arrested at least three times on drug charges and spent three years behind bars, from 2005 to 2008.

In 2010, he also was charged with endangering the welfare of a child because of an argument a male relative had with a woman over child care, according to the Long Island Press.

Additional reporting by Dana Sau­ch­elli, Ben Feuerherdand and Beckie Strum