Only a week after he said that Metallica's new album is "25 percent done," Kirk Hammett has hinted at another potential snag. In a recent interview, he said he has lost his iPhone, on which he had been stockpiling riffs.

"I lost my iPhone [with] 250 musical ideas," he told the Jasta Show. "And I was crushed. It didn't get backed up. And when it happened, I was bummed out for about two or three days. I walked into the house. My wife saw me and she said, 'Uh-oh, what's wrong? Did you get a phone call from a relative?' I said, 'No.' She said, 'What's going on?' I told her, and she understood."

Hammett said this happened roughly six months ago, and still he hasn't found it yet. But he admitted it may turn out to be a silver lining in the creative process. After all, they originally had 800 riffs, so losing 30 percent of them, for Hammett, suggests that those have already been eliminated from contention. "I can only remember, like, eight of 'em. So I just chalked it down to maybe it just wasn't meant to be and I'll just move forward with it."

Like a writer with a notepad, Hammett regularly plays or hums musical ideas into his phone. And usually, he's made sure that "the phone is f---ing backed up." But for whatever reason, that isn't the case this time, and he passed the lesson on to younger generations.

"All you musicians out there who use your phone, make sure it's backed up. Right?!"

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