Overwritten?
Sounds like there was something on that tape that wasn’t meant to be disclosed.
It must be a fascinating life you lead thinking EVERYTHING is a conspiracy. The window (false door) blew out because someone at Boeing screwed up, and the pilots did a nice job of landing the plane. No one got hurt. End of story.
No, they record continuously like an old-fashioned loop tape recorder (I think at one time they WERE loop tape recorders), so whatever is older than X amount of hours is gone.
No, the authorities (NTSB investigator) didn't request the recorder be turned off (circuit breaker pulled) when starting the investigation upon landing.
Incompetence is not conspiracy.
Sounds like Rose Mary Woods is working for Alaska Airlines.