I have a black screen

[Marie22xx]

I have a black screen computer turns on lights is on. When I plug to another monitor it works 

[WAWood]

@Marie22xx 

Do I understand you to say that when you plug in an external monitor, you can use the All-in-One without issue?

IF this is the case, then the screen has failed, because if it was the video chip, the external screen would also be black.

Replacing the screen on an All-in-One is very difficult and costly.

We are not able, or permitted, to provide any repair estimates or equipment prices.

For this information, you would need to contact an HP Repair or Service Center.

Since you live in the U.S., here is a link to the HP Service Repair Centers:
https://www.service-center-locator.com/hp-hewlett-packard/hp-hewlett-packard-service-center.htm

If that link does not provide you sufficient information, then use the main HP link:
https://support.hp.com/us-en/contact-hp?openCLC=true

I've found those links to be unreliable if you're using Win10 and the new Edge Browser; so if you are, you need to use something else, like FireFox.

Good Luck