Green Day frontman Billie Joe Armstrong is out of the hospital and back in L.A. following a medical scare ... and upon his arrival Monday, the singer mouthed to TMZ that his voice is completely gone.
The band was supposed to play a show in Italy this weekend, but the guys were forced to cancel the gig when Billie Joe was "rushed to the hospital due to illness."
The rest of the band released a video statement saying, "We're beyond devastated ... We're as sad as you guys are. Billie's extremely upset about it."
The guys never revealed the nature of Armstrong's illness ... but now it's obvious, it has something to do with his throat.
On his way out of the airport, we asked Billie Joe about some other stuff ... but for some reason, he didn't have much to say.