Legendary country-rock singer Linda Ronstadt has revealed her battle with Parkinson's disease, which has completely robbed her of the ability to sing.

In a new interview, Ronstadt says she was diagnosed just eight months ago, but she may have experienced the first symptoms as far back as eight years ago. The singer knew "there was something wrong" with her voice, but ascribed it to an illness from a tick bite. "My health has never recovered since then," she admits.

“I couldn’t sing,” Ronstadt tells AARP, “and I couldn’t figure out why. I knew it was mechanical. I knew it had to do with the muscles, but I thought it might have also had something to do with the tick disease that I had. And it didn’t occur to me to go to a neurologist. I think I’ve had it for seven or eight years already, because of the symptoms that I’ve had. Then I had a shoulder operation, so I thought that’s why my hands were trembling."

The 67-year-old singer was taken completely by surprise when doctors finally gave her the news. “Parkinson’s is very hard to diagnose, so when I finally went to a neurologist and he said, ‘Oh, you have Parkinson’s disease,’ I was completely shocked," she admits. "I wouldn’t have suspected that in a million, billion years."

Ronstadt was one of the leading lights of the country-rock movement that centered in California in the '70s. She released a string of commercially and critically successful albums that helped break down many of the stereotypes for female vocalists, and in the process became the best-selling female artist of the decade. She is widely regarded as rock music's first true female superstar.

Though she had most of her success in rock music, Ronstadt also had country hits, including 'When Will I Be Loved' and 'Blue Bayou.' Her early backing band featured Glenn Frey, Don Henley, Randy Meisner and Bernie Leadon, who split off to form the Eagles.

She later worked with Dolly Parton and Emmylou Harris on 1987's 'Trio' album, which reached No. 1 on the Billboard Country Albums chart and won them a Grammy. They teamed up again for 'Trio II' in 1994, winning another Grammy.

Sadly, the voice that many critics have recognized as the best of a generation is now forever silent. Ronstadt, who now walks with the help of poles on uneven ground and uses a wheelchair when she travels, says she "can't sing a note" anymore, due to the progression of her disease.

“No one can sing with Parkinson’s disease,” she says. “No matter how hard you try.”

The singer is releasing her autobiography, 'Simple Dreams,' on Sept. 17. The book does not delve into her diagnosis or the loss of her voice.