HP Photosmart 8150

Most printers have a 'reset' function. It is very often not a a separate button but achieved by pressing certain combinations of buttons with the power off. then with the buttons pressed powering up again. Trouble is the manual does not tell you- You have to figure it out for your self by trial and error- and with so many models out there, I cant tell what to do But here is a website that may www.fixyourownprinter.com

I had the exact same problem as you. For me the black cartridge ran out and when I went to change it, it never recognized the new cartridge. I tried to go back to the old cartridge even and it wouldn't recognize it. This became very frustrating and I tried everything that the other message boards and HP's site said. Before I found something that worked I tried:

- Running all the included HP diagnostic software (you know, the head alignments, head cleaner, yadda yadda yadda).
- Cleaning the contact points about 7 times with a little rubbing alochol, cotton swabs and even an eraser.
- Easily 20 power cycles, sometimes leaving it disconnected from power for a half hour or so.
- Trying the factory reset via the printers onboard software
- Yelling obscenities

Anyway, the post by jackboy before me gave me the idea about a more intensive factory reset (thanks!). I started looking into all over the web but could not find and leads so I broke down and started a chat session with a HP rep via their site and went through the whole long diagnositc tree to no avail but at the end I asked them about a physical factory reset method and low and behold the rep found me this:

http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&dlc=en&cc=us&docname=c00260524&product=397810&printable=no&encodeUrl=true&

I followed the steps and even though it describes an entirely different problem, 2 minutes later the printer was working fine like nothing had ever gone wrong. Since it was this site which led me on the right track I figured it was only proper to share my knowledge back to the community.

Obviously I cant gaurantee that this will work for you, but hopefully it does:

1. Disconnect any USB cables attached to the printer and remove any memory cards from the drive bay.
2. Restart the computer.
3. Remove any paper from the paper tray.
4. Unlock the ink cartridge locking clips.
5. Remove all printer ink cartridges.
6. Lock down the ink cartridge locking clips.
7. Close the main printer door.
8. Turn off the printer using the power button and wait for the printer to shut down before proceeding to step i.
9. Unplug the power from the back of the printer.
10. Unplug the power adapter from the wall outlet.
11. Remove the rear access door.
12. Locate and then roll the internal rollers in an upward direction until a clicking sound is heard.
13. Reinstall and lock the rear access door.
14. Connect the power adapter to a wall outlet.
15. Reconnect the power cable to the printer.
16. Turn the printer on.
17. Re-insert the paper into the input tray.
18. Wait for the appropriate missing cartridge error to verify that the printer recognizes this error.
19. Re-insert one ink cartridge only, to minimize confusion in case one of the cartridges is defective, and print an internal test page.
20. If no errors are found, insert the other ink cartridge(s) and ensure that they are functioning by performing internal test pages or calibration pages.