How do you fix an hp printer when it says “ missing or failed printhead”?

First, try resetting the HP printer. ...

Then remove the power cord from the back of the printer.

Thereafter, unplug the power cord at the wall.

Wait a few minutes, and then plug the printer's power cable back in the wall socket.

i just go to the help center

Remove it or send it in for repair.

The print head cannot be replaced by the consumer, and there may be a sensor issue.

Replace the printhead, it’s not hard.

Have you tried turning it off and turning it back on again?

You buy a new one.

The printer does not print, and a printhead error message displays on the computer or printer control panel.

In many cases, the only way to resolve a printhead failure is to replace the printhead, if it is replaceable. If the printhead is not replaceable, the entire printer must be replaced or serviced.

see owner's manual.  then ask on the HP support pages

Cheapest fix is to buy a new printer.

Replace the printhead or, in fact, the whole printer.

Sadly, you don't indicate which specific HP Printer it is that you have so we can't look it up on YouTube on how you actually go about removing the printhead from your specific printer.  (There are slightly different methods for different printers, and failing to do it correctly COULD result in you totally incapacitating your printer.)

It MAY be that there's simply something obstructing the connections between the printhead and the actual printer. i.e. something as simple as ink MAY have gotten onto the connections.