My main PC is a HP, maybe 2008ish? It's on Win 10 with 3 internal SATA HDDs:

Seagate ST3500630AS (Boot)
Seagate ST31000340AS (Disk 1)
Samsung HD103UJ (Disk 2)


Disk 1 has gone missing, it's no longer visible in This PC or Storage Manager, but shows up in BIOS (hence model numbers above).

I've tried swapping SATA sockets on Disk 1 & 2 but no change.

If it's visible to BIOS then surely Windows should see it too, maybe with a corrupt or missing volume?

What can I do to diagnose/recover? I don't have an external USB enclosure to test the drive off another PC, should I get one?