no john cena has never won a Grammy
no
No
"Wax Simulacra," by The Mars Volta, won Best Hard Rock Performance at the 51st Grammy Awards.
Of course! He's won the most Grammy's ever in HIStory!
Demi Lovato has never won a Grammy
yes
Metallica.
Yes, they won 1 in the 2011 Grammys. :)
Zero
Grammy Lifetime Achievement Award - as a solo artist in 2012
No but she does have two nominations.