Great news, that you were able to locate the Qubes installation - and that it’s working! 
I don’t have your hardware, so I’m only guessing … but it could be a matter of renaming some folders, as @apparatus linked yesterday:
or since it was on hd2, maybe the BIOS only look at hd0/hd1?
Since you have three harddisks, is there another OS, that you need to be aware of?