Lost drive

I have a homebuilt computer with an ASUS P7P55D motherboard and three
Western Digital 500 GB hard drives. I built this computer a few years
back and it has worked very well until recently when one of the drives
"disappeared" and I can not get it to come back from ghost land.

The three 500 GB hard drives are set up with C: being used for the OS
and my client software. D: is used for all my documents, etc. F: is
used as a backup. All the drives show a large amount of free space and
all the checks like defrag, bad sectors, computer memory check, etc.,
indicate no problems at all.

A few days ago drive D: disappeared and I can not figure out what
happened. I bought a new Western Digital hard drive and put it in the
same slot, after removing the old one but it also is not discernable
in any way. I can't format it or even find anything that indicates its
presence.

I can switch the SATA connections that normally connect to D: and put
them onto F: and this drive seems normal in every way. This seems to
indicate that the motherboard circuits for the drive are functioning
okay.

If I put the SATA connector that normally goes on F: onto D: I still
can't find a trace of D: and none of my software can locate their
files that are stored on drive D: This same SATA connection will work
as it should when connected to either drive D: or F:

What could cause a drive to go into hiding like this, and what can I
do to rectify the situation?

Thanks in advance for any suggestions...other than for me to go jump
off a bridge. Gordon