Hey There, I am Sofia Carter. If your HP printer goes down and shows HP deskjet offline error, you'll need to troubleshoot a variety of problems. This must be accomplished step by step and in a methodical manner. You must look for issues with the power supply, USB cable, driver files, cartridges, and sleeping mode. The benefit of troubleshooting is that you will be able to pinpoint the source of the issue. Once the issue has been discovered, it is very simple to resolve.