If your HP DeskJet 2800 printer is not printing, several common troubleshooting steps can resolve the issue:

1. **Restart and Reset the Printer and Computer**: Power off both the printer and the connected computer or laptop. Wait a few minutes, then power them back on. You can also perform a hard reset by unplugging the printer for about 30-60 seconds before plugging it back in[1][2][3].

2. **Check Printer Status and Print Queue**: Ensure the printer is online (not showing offline status) and set as the default printer on your computer. Go to **Settings > Devices > Printers & scanners**, select your HP DeskJet 2800, open the print queue, and clear any stuck print jobs[1][3].

3. **Verify Network/Wireless Connection**: Make sure the printer and your computer are connected to the same Wi-Fi network. Disable firewall or antivirus temporarily to ensure they are not blocking the printer communication[1].

4. **Inspect Ink Cartridges**: Confirm that genuine HP ink cartridges compatible with your model are correctly installed. Remove and reinstall cartridges to check for any protective tape that might have been left on. Replace cartridges if they are empty or low[2][3].

5. **Clean Printhead**: If printing issues persist, particularly with black ink not printing, clean the printhead either using the printer software or manually with a soft, warm damp cloth (let dry fully before reinserting)[2].

6. **Update Firmware and Software**: Visit HP’s support site to check for and install any available firmware updates for your DeskJet 2800 model. Also, ensure the HP Smart app and your printer drivers are up to date[3].

7. **Run the Windows Printer Troubleshooter**: On Windows PCs, use Settings > System > Troubleshoot > Other troubleshooters > Printer to detect and fix printer issues automatically[1].

If these steps do not resolve the problem, there may be a hardware fault or deeper software conflict requiring professional service or contacting HP Support.

These instructions are based on HP support community advice and official HP documentation for the HP DeskJet 2800 series models[1][2][3].