Mountain Lion won't mount backup drive
I recently upgraded to Mountain Lion from Lion.
For some reason, the upgrade did not go well, so I went to the Genius Bar.
Genius bar man asked if I had backed up my data, I said yes, in fact just that morning.
He wiped my drive clean and reinstalled Mountain Lion.
Ever since then, I cannot access my backup LaCie drive.
It does not show up on the desktop.
Any ideas??? Disk utility says both hard drives are OK.
Mac mini, Mac OS X (10.6.8), shows events from two months ago