Hi -- And many thanks for the idea.  I had never heard of such a fix before.  It, regrettably, didn't change anything.  Whatever I plug into the 'SATA-0' port (even a brand new, unformatted, 1 TB drive) is 'identified' in 'set up' as what appears to be a 'D:' drive.  This leads me to believe that what appears in 'set up' has somehow been added to the BIOS files, something I didn't know was possible.  Is it possible that my BIOS files (A22) have somehow become corrupted?  If so, how do I restore the BIOS files to their original state?  Now I am really confused!  As I may not know what is going on, my supposition may be all wrong.  Accordingly HELP is still sought!
A Dell 755 used as a secondary PC no longer recognizes the 'C:' drive after the system battery failed and was replaced.  When I put the PC in 'Setup' mode, everything seems OK EXCEPT no C: drive is recognized when I try to set up the boot sequence.  A drive attached to the 'SATA-0' port on the motherboard appears to be recognized as a 'D:' drive.  I have, one action at a time, (1) replaced the old hard drive with a brand new hard drive, (2) replaced the hard drive connecting cable, (3) wiggled both ends of the hard drive connecting cable in their respective sockets to try for a more positive connection.  Is there any possibility that this is a BIOS problem or that BIOS information was lost when the system battery died?  Suggestions, repair approaches, and guidance on how to proceed are urgently sought. I'm in my mid-80s and am baffled as I have never seen this type of problem before.  Thank you, in advance, any responses.  At my age, the more detailed the responses are is very helpful.
Optiplex 755 no longer recognizes C: drive after CMOS battery replacement