David Cassidy barely could buy a break in the 1980s, then he woke up and felt loved again one morning in the ’90s.

What a difference a decade makes.

“I came back in the music business (in the late ’80s) and began writing songs that people started covering,” Cassidy said recently, “and that’s how I got signed back in ’90 to do the (self-titled) Enigma album, which had ‘Lyin’ to Myself’ on it.

“From there, it was like walking out the door and everybody goes, ‘Wow! It’s you, you’re like cool.’ And I’m like, ‘I am? Oh, okay.’ It literally felt like that. One day I would walk down the street and instead of being ‘the guy from the ’70s,’ I was like this cool guy. I’ve always found it really amusing.

“But I’ve always felt a certain kind of responsibility about being somebody that was viewed as an idol or a role model. I always took that really seriously. The fans changed my life. If it hadn’t been for them, I might be pumping gas. I don’t take that lightly.”

Twenty-nine years ago this month, Cassidy was simply the 20-year-old son of veteran actor Jack Cassidy, but after winning the role of Keith Partridge, the eldest son on the ABC sitcom “The Partridge Family,” his world would turn upside down.

Playing opposite real-life stepmother Shirley Jones, Cassidy recorded lead vocals on 18 songs before the series premiered Sept. 25, 1970. Two weeks later, the prefabricated Partridge Family debuted on Billboard’s pop chart with their first single, “I Think I Love You.” By Nov. 21, they leapfrogged the Jackson Five’s “I’ll Be There” to hit No. 1. It sold more than 6 million copies worldwide.

“The Partridge Family” wasn’t a TV ratings smash, but like its Friday night counterpart, “The Brady Bunch,” it was hugely popular with kids. They snapped up everything from Partridge Family albums (five straight went gold) and 45s (seven went Top 40) to Partridge Family lunch boxes and teenybopper magazines with Cassidy’s toothy grin plastered on the cover.

Cassidy also toured the world as a solo singer, playing sometimes to 50,000 screaming fans in stadiums. His early career reached a tragic peak 24 years ago this week when a 14-year-old girl suffered a fatal heart attack and more than 1,000 needed medical treatment during a show May 26 in London.

“I think I had announced before the tour had started that this was it,” Cassidy said, “and the last date booked was in Manchester, and this was the next-to-last date (in London). I had planned on leaving and retiring.

“What happened was very unfortunate. I spoke with the parents of the girl. She didn’t get crushed or anything; she had a heart condition. She got so excited about it, she just lost control and died. It can happen anywhere. She had it and her parents were very aware of it. They said to me, ‘We don’t blame you at all,’ and I think she probably felt that would be the way she wanted to go. At least she found peace with herself.

“My concerts were events in those days. It wasn’t like the music was the thing, it was the event, playing to 40,000-50,000 people. There was chaos and pandemonium and hysteria going on. It became, from a security standpoint, a very difficult thing. I was taking 36 people with me, most of it security. It got so out of control, I needed to leave it. The only way you can move on from that is to close the cover on the book and say, ‘That was as good as anybody can do it.’ I’m proud of what I did and I’m proud of the fact that I had such an impact, and I hope they allow me to move on and do other stuff.”

Cassidy did move on. Even though the 1980s were particularly lean for him back home, he resurfaced in England with a Top 10 hit, “The Last Kiss,” in 1985. By the end of 1990, he was back in America’s good graces with “David Cassidy” and the Top-30 single, “Lyin’ to Myself,” his first legitimate hit in 18 years.

It only got better: A) He hosted VH1’s “8-Track Flashback” for several years and starred in several Broadway plays, including “Blood Brothers” with stepbrother Shaun Cassidy; B) “I Think I Love You” popped up in the film “Scream 2” and an award-winning Levi’s commercial; C) He also was the executive producer/creator of the short-lived Fox sitcom, “Ask Harriet,” and currently is starring in the stage production of “EFX” at the MGM Grand in Las Vegas.

During his spare time in Las Vegas, Cassidy teamed with producers Peter Bunetta, Scot Rammer and Dino Esposito to record “Old Trick, New Dog,” Cassidy’s first album in nearly eight years. The album, on the indie label Slamajama, was released May 12.

“Old Trick, New Dog” is fresh and contemporary, with a tip of the hat to the 48-year-old Cassidy’s past. Along with new songs composed with wife Sue Shifrin, Cassidy puts a new, palatable twist on the Partridge Family hits “I Think I Love You,” “I Woke Up in Love This Morning” and “I Can Feel Your Heartbeat” and his 1972 solo recording “Ricky’s Tune.”

“It’s the first CD, honestly, that I’ve made that after I was done with it and had heard it a hundred times,” Cassidy said, “I put it back on a month later and I really enjoyed listening to it. I wanted to hear it. I have to honestly say never before did I do that, because I was so tired of hearing (the previous albums).

“I’m excited about the reaction and the fact that there’s so much interest in it and a great reaction at radio for ‘I Think I Love You.’ Hopefully, I’ll get out there and they’ll add it and play it. Therein lies the trick.”

By Cassidy’s own estimation, this is the 18th album of his career, dating back to 1970.

“That’s a lot of records,” he said. “I was thinking about it the other day, there are probably only three or four recording artists that are still making records and still alive and doing well from those days.

“I’ve been really fortunate that I’ve been successful in various things, like television, on the stage and records. I think I have, and I hope I always have, the opportunity to record. I love the process of it. It’s like taking a canvas and painting.”

BWF (before we forget): Cherish David Cassidy on the Web @ davidcassidy.com, or if you wanna come on get happy, check out partridgefamily.com.