HP Officejet 8720 scan function can't find printer after W10 upgrade

After I did the W10 install the printer worked, and I thought I was all ok until I tried to scan today.

The printer is connected via USB.

Print and Scan Doctor said it couldn't find the printer. When I press the scan button on the printer it says it can't find the computer.

I can't get the information I need from HP. The printer is out of warranty and the virtual agent doesn't understand my question.

I was impressed that the USB connection for the printing function migrated seamlessly to w10, because it was very hard to set up initially n W7. But I need to scan too!

As usual, I would appreciate your help

I don't have the printer to help you, but --

1. I find my PC forgets that the printer is connected. I used to pull my hair out rebooting but really one unplug and replug fixes it every time. And it didn't start that way with Windows 10 but developed about a year ago.

2. I'd be all over an HP forum to see if this is a common issue with a suggested fix. Is there nothing there? Have you already been here --

https://h30434.www3.hp.com/t5/Scanni...0/td-p/6546525

Pool Man, thanks for the prod to check the HP forum. When I did that to try to set up the printer initially I got a lot of advice that did not work, but maybe they will come through for me this time. I posted my query there too.

I don't see the scan dialog box, just the message that the scanner cannot be found and the option to click ok.

Caledon Ken, you posted while I was reading Pool Man's post, and I will follow your steps tomorrow. Thank you so much. Maybe following your instructions will even enable the fax function, which has never worked on this printer (although it did on the previous HP printer, connected to the same computer, on the same phone jack). When I plug in the fax cable (the one supplied by HP) our whole phone system is disabled. We have a copper line.

Caledon Ken, good thought, but I just checked and I think it is plugged in right. There are indeed 2 phone jacks on back. I had left the fax cord plugged in to the computer, on the one labeled 1-LINE. The other one is labeled 2-EXT, and came with a dummy blocker plug. I checked the printer manual, and indeed the fax is supposed to be plugged into 1-LINE.

FWIW I have an 8720, connected via wi-fi, working perfectly in Win10. USB should be no different.
I installed the HP software and followed the on-screen instructions. I didn't connect the Printer first, which potentially can cause problems or wrong drivers.

I would do what Calendon Ken suggests, with one additional step. After eveerything is uninstalled and before you start the new install, reboot (restart) the PC. Then do the new install.