When yourhp printer says out of paper, it is an issue usually related to paper jamming. To fix this, follow the steps below: 

1. Cancel the print job from your computer.

2. Remove any jammed paper from the tray and sheet feeder.

3. Press the start button and check if the issue still appears. If it shows an error, then follow the next step. 

4. Turn off the printer by pressing the power button.

5. Check if paper is jammed inside the scanner unit.

6. Close the scanner unit and press the power button.