Johnny Rotten's devastated by the death of Prodigy frontman Keith Flint ... and now he's on a mission to personally help other musicians battling suicidal thoughts.
The Sex Pistols legendary frontman was heading into Monday night's premiere of the "Punk" docuseries at Hollywood's SIR Studios ... and he was clearly broken up over Flint taking his own life. Johnny tells us The Prodigy singer was a good friend, but he believes he was "left alone" and "destroyed."
The iconic punk rocker says he's troubled by what he thinks is a sad new trend -- rockers not looking after each other. Johnny has a loving message to others who are hurting, though ... come talk to him.
As we reported ... Flint was found dead Monday in his home outside London, and his bandmates say he died as a result of suicide.
Johnny's taking it pretty hard.