Startup drive missing?

At start up I get the gray folder of death of the flashing?. I have ran the diagnostics test which came up with the message. There may be an issue with storage device reference code: VDH 002. I’ve also booted in the recovery mode which it doesn’t let me get any farther past to where I would reinstall macOS. However, I am being like you call so-called hack for the last two years and somebody has downloaded something into the system. Part of it. It came up once and then it went away. I’m by far no expert on this 55 year old, retired career army man, so I need lots of help