David Crosby's music has ''saved [his] butt'' following the death of his biological son Beckett.

The 78-year-old rocker was the sperm donor for Melissa Etheridge and Julie Cypher's son - who died as a result of a drug addiction at the age of 21 last month - and he admitted his passing ''blew [him] out of the water'', but he's since found solace in the recording studio.

He told Uncut magazine: ''[Music has] saved my butt - again. I'm having a hard time in my life right now. I just lost a kid. That blew me out of the water, man. The country I love is in desperate throes.

''The truth is, man, I swear to God - I got two magics, my family and the music, and I'm reaching for them both real hard.''

David is currently a member of CPR with his son James Raymond - who he reunited with in 1995 after putting him up for adoption in the 1960s - and guitarist Jeff Pevar, and he credits his offspring for reinvigorating his career.

He said: ''Most people peter out in their sixties and seventies - and I would have too for sure.

''I knew the exact moment when I knew I could work with James. I gave him the words of 'Morrison' and said, 'Here, try and write some music for this.'

''He came back with a cassette and I remember sitting in his tiny little Japanese pick-up, listening to the tape and knowing that my life was changing.''

The former Crosby, Stills, Nash and Young star previously described Beckett's death as a ''test''.

Responding to one Twitter user who described him as a ''donor who played no part'' in raising Beckett, he replied: ''Not true.''

A fan then sent a message of condolence over Beckett's death.

They wrote: ''While I know that you were a surrogate, I also know that you just lost a son. I'm sorry, I know you've had a rough year.''

David replied: ''Maybe it's a test.''