Can't enable bluetooth, 12.04, Shuttle desktop

Can't enable bluetooth, 12.04, Shuttle desktop

I have a home-built Shuttle desktop. I'm running 12.04. I'm confused about
some very basic bluetooth truths.
I just built the desktop last year, with pretty respectable components,
from a Shuttle barebones system. It was my first build, and there's a lot
I don't know, but I did manage to make myself a system I like very much.
I don't remember specifically including bluetooth capability into the
system, but I think I'd have picked up on it in my research if I had been
building a system without that; it's definitely something I'd have wanted
to include.
I'm trying to pair a bluetooth headset with the system. It doesn't
automatically pair, and headset directions say to go the bluetooth menu on
the computer and select "Search for" or "Add new devices." I went to
settings/bluetooth, and saw that bluetooth was off, and wouldn't respond
to my attempts to click it on; the light gray window's light gray print
says, "No Bluetooth adapters found."
I'm running a Logitech keyboard and trackpad from a Logitech dongle.
Pairing those to the one dongle was a trick; I had to do it on my ancient
windows laptop, but once I did, both devices worked for my Ubuntu Shuttle
system via the one dongle.
Thinking that I must have done something to the Logitech dongle when I
unified two devices to it — maybe I somehow shut out everything else in
the process — I inserted the spare Logitech dongle into my machine, but no
joy with the headset, nor with the Ubuntu settings.
Meanwhile, what I've read as I've browsed on this forum made me think that
my system maybe shouldn't even need a dongle for bluetooth to work. It's
very confusing!
In short, I don't understand why my machine isn't finding the bluetooth
adapters, and I'd also like to know whether there's some bluetooth
capability on my machine that I could get to if I knew how.
One poster said that he discovered that his network adapter had been
disabled by the manufacturer, and, once he fixed that in the BIOS
settings, his problems were over. I looked in my BIOS, and I couldn't find
anything about a network adapter.
I wonder whether it's a Logitech proprietary problem; they don't seem to
like Linux much. Other posters have said they've managed to make all their
devices work via their Logitech dongles, but they suggest command-line
measures, and, being somewhat command-line illiterate, that never seems to
work for me. There's always some hole in the directions, some assumption
that I know something the directions gloss over, and I can't afford the
frustration of trying one set of directions after another.
Does anyone have any suggestions?
Thanks.