Printer (hpdeskjet840c) will not print automatic font

Hi i have an asus win 10 tower pc and an old printer which used to work fine until recently.basically if i try print a page with automatic font/black the printer appears to print but page is blank as if no ink is used.i know there is black ink as my brother printed the same doc from his laptop.if i change the text to colour on my pc ie blue it prints fine.
One hunch i have is a windows update caused it.my dads laptop had same problem while mine worked.but now mine has the problem.
Ive removed the device and rebooted and reinstalled but still the problem persists.
I troubleshooted the printer and win 10 says usb 2 is my printer but usb 3 is my pc.i used hp print docter and it said everything was fine.
Any ideas?

That's an old printer....as I had one about 20 yrs ago. A basic, simple printer that worked. I'm having a very hard time trying to find drivers for it. That being said....I would start looking for a new printer....one that is made to work with windows 10.

Worked perfectly up to a week ago when i noticed this problem.

Win 10 finds the printer when searching for it fine.ive seen threads for same problem on another site from a few years ago that wasnt solved so its not just win 10.

Windows 10 will find the best driver it can or use it's generic driver to get hardware to work. Some stuff may work and some stuff won't. As far as your printer goes....it's not windows 10 compatible and I doubt HP will create driver/software for it. From what I've been noticing, a lot of older hardware that used to work with windows 10 is starting to not work with it as MS updates are being installed. No proof that the updates are causing the problem but there is a definite trend happening.

Thanks maybe ill look into a new printer if i can get one for around €50

Its just the fact that every other colour prints including the test page which is automatic font.which is wierd.

What version of Windows is the laptop running? Hold down the Windows key and press R, type winver, post the whole line. Some newer computers come with USB 3.0 ports which can 'fall back' to USB 2.0 but I have seen HP printers that have trouble with USB 3.0, have to assure plugged into a USB 2.0 port. USB 3.0 usually has blue centers while USB 2.0 ports have black centers, using the correct type cable also makes a difference. If USB 3.0 devices need a particular cable the device end will have a differently shaped cable, there's 2 types of ends depending upon the maker. Generally the keyboard and mouse will use ports nearest the power supply and they will be USB 2.0, available before the OS loads, USB 3.0 needs drivers that don't load until the OS does.

The Printer is too old. I used to have a HP 900 series printer and Windows 10 only provides a basic driver. The useful features in the full feature driver were just not available.
It did not work 'perfectly' that's for sure. No doubt a similar scenario for an 800 series printer.

To be honest just buy a newer one and save any aggro.