Hmm. So, try removing it from your list of printers, in System Preferences. Unplug the printer. Turn it off. Turn it on, then plug it back into your Mac. Does it show up in the list of available printers? What's the status of the printer, still offline?
You might need to click the + button and add it manually.
Do you have another Mac capable of using the printer? If so, try plugging the printer into that.
I really don't know what I did. I know I ran System Update and got the latest Java installed, which meant a restart. But I'd already done a restart, and that hadn't helped.
Now if I could just figure out why it went offline, and why it seems to have come back online. I'm sure it will happen again, and I'll go through the same frustration.
I did unplug it from the iMac, left it turned off for a while, and then plugged it back in and started it up. It was always there on the list of available printers.
Even when it was "offline" the lights on it blinked when I tried to print. Just stopped and then the utility said it was offline.
I print so rarely, that I will go through this frustration again, I know. Sigh, wish I could go back to my old trashed LaserWriter. Oh well, I guess this is progress. I think.
I'm just impressed that I decoded the thread title correctly. But then again, I have yet to have any luck with HP products either. For printing I run Canon and Epson.