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Living out of the spotlight for more than 20 years in Carmel, Calif., Doris Day was quite surprised to get a certain call last January. It was Colin Firth, wanting to confess his schoolboy crush. "He told me when he was a kid, he fell in love with me and wanted to meet someone like me," says Day, 87. "It was so cute because I had to say I really didn't even know who he was!"

Firth is just one of the many who have been smitten with America's Sweetheart of the Mad Men era, best known for singing "Que Sera, Sera" and starring with the likes of Cary Grant and Rock Hudson. One of the top box office and pop stars of the '50s and '60s, Day left Hollywood in the early '80s to live on her 11-acre estate. "It wasn't the city I knew anymore," she says. "If I had stayed, I might be playing a grandmother-who knows! But I love living in a small town. I have my pets around me, and I like to answer my fan mail." Now she's released her first album in 17 years, My Heart, recorded over three decades, with pop hits, ballads such as "You Are So Beautiful" and a novelty song about a wine-drinking horse. (Proceeds go to her animal foundation.) The attention to her new music, says Day, "is funny and unexpected."

Born Doris Kappelhoff in Cincinnati to music teacher William and homemaker Alma, Day first studied singing as a teen while on two years of bed rest after a car accident. In 1945 she broke through with her big-band hit "Sentimental Journey" and became famous for her sunny disposition. Yet Day suffered plenty of personal heartbreak, including three divorces and a lawyer who squandered her millions. "I have had a lot of sorrow, and I still feel that," says Day. Her biggest heartache was the death of her son Terry Melcher-who produced many ballads on her new album-from melanoma in 2004. "I had him when I was [18], so we were like sister and brother," she says. His passing "was really hard. But I keep him with me."

She also treasures memories of her co-stars such as Rock Hudson, who played her love interest in several romantic comedies. "He called me Eunice," she says. "He'd come into the makeup area hollering, 'Eunice, I'll be over with a doughnut!'" When he was dying of AIDS in 1985, she saw him for the last time. "I'd bring him a big lunch and try to feed him," recalls Day. "He'd whisper, 'I can't eat.' When we parted, he held onto me. I was in tears. But he's in heaven now. Almost everybody I love is."

These days pals include Paul McCartney, another surprise fan. "When he first called, I said, 'Who is this really?'" she says. "He's a rascal! He calls me at 3 a.m. [from England] and scares me! I say, 'I'm sound asleep, what's the matter?' and he says, 'It's your buddy, Paul!'"

Her humor has always been her secret weapon. "I love to laugh," says Day. "It's the only way to live. Enjoy each day-it's not coming back again!"

People TABLET BONUS PIX Doris Day over the years