He thought he was a woman trapped in a man’s body — but it turns out he’s “just another boring straight guy.”

ABC News editor Don Ennis strolled into the newsroom in May wearing a little black dress and an auburn wig and announced he was transgender and splitting from his wife. He wanted to be called Dawn.

But now he says he suffered from a two-day bout of amnesia that has made him realize he wants to live his life again as Don.

“I accused my wife of playing some kind of cruel joke, dressing me up in a wig and bra and making fake ID’s with the name ‘Dawn’ on it. Seriously,” Ennis wrote in a memo he posted to the newsroom bulletin board Friday, explaining his shock after he woke up from what he called a “transient global amnesia” last month.

The memo was first obtained by the website NewsBlues.com

“It became obvious this was not the case once I took off the bra — and discovered two reasons I was wearing one,” he said, referring to his hormone-induced breasts.

“I thought it was 1999 . . . and I was sure as hell that I was a man,” Ennis said in the e-mail titled “Not Reportable, Very Confirmed.”

“Fortunately, my memories of the last 14 years have since returned. But what did not return was my identity as Dawn,” said Ennis, who had been wearing lipstick, skirts and heels.

“I am writing to let you know I’m changing my name . . . to Don Ennis. That will be my name again, now and forever. And it appears I’m not transgender after all.

“I have retained the much different mind-set I had in 1999: I am now totally, completely, unabashedly male in my mind, despite my physical attributes,” he said.

“I’m asking all of you who accepted me as a transgender to now understand: I was misdiagnosed.

“I am already using the men’s room and dressing accordingly,” he noted.

“It’s so odd to be experiencing this from the other side; as recently as last Friday, I felt I was indeed a woman, in my mind, body and soul.

“Even though I will not wear the wig or the makeup or the skirts again, I promise to remain a strong straight ally, a supporter of diversity and an advocate for equal rights and other LGBT issues including same-sex marriage.”

Ennis had previously told friends that he suspected his sex mix-up happened because his mother gave him female hormones as a child that made him look and sound young to prolong a bit-part acting career, but he ended up developing breasts and started thinking he was a woman.

He explained he had gone to the National Institute of Health in Bethesda, Md., for testing last month to understand why his mind and body changed from male to female. He said he learned it was a hormone imbalance that could be fixed.

A week after he was discharged, his wife rushed him back to the hospital because he thought he was having a seizure and was experiencing a “drastic loss of memory.”

Don added that he now feels “fantastic” as a man again.

And he said he hopes that with the hormone treatment and surgery, things will only get better.

Despite his short stint as a woman he told colleagues in the letter that he promises to remain “a strong straight ally and a supporter of diversity and an advocate for equal rights and other LGBT issues including same sex marriage.”

He plans to change the gender and name on his driver’s license, work ID and e-mail.

He called his three-month odyssey into the world of women “a tremendous gift.”

“I know my wonderful colleagues will no doubt make it easier for the next person to transition at ABC,” he wrote.

The startling he-to-she-back-to-he move came after Ennis had publicly announced on Facebook in May that he was leaving his wife of 17 years, Wendy, to become a full-time woman.

The Connecticut resident has now assured friends and colleagues that his switch back to being a man isn’t a joke.

“The new change I’m revealing to you today did not arise because I couldn’t hack it, or people wouldn’t accept the new/real/female ‘me,’ or I had trouble finding shoes that fit (Oh, I found plenty, more than I could afford),” he wrote.

“Even my beloved, who had encouraged me to be true to myself at the expense of our marriage, had finally accepted my new identity.”

The editor had said female was “the gender that ruled my body and now my mind.”

But Ennis said in last week’s e-mail to colleagues that he was reversing course again, declaring: “No, I’m not f–king with you. No this is not a joke. No, this is not an episode of ‘Would You Fall For That?’ ”