Fixing an HP printer that is offline in Windows 10 can be done by following these steps:

1. Check the Power and Connectivity: Ensure that the printer is turned on and properly connected to your computer.
2. Restart the Printer: Turn the printer off, wait for a few seconds, and then turn it back on.
3. Restart your Computer: Shut down your computer, wait for a few seconds, and then turn it back on.
4. Update the Printer Driver: Visit the HP website, download and install the latest driver for your printer.
5. Change the Printer Status to Online: Right-click on the printer icon in the Windows taskbar, select "See what's printing," click on "Printer" in the top menu, and choose "Use Printer Online".
6. Restart the Print Spooler Service: Type "Services" in the Windows search bar, click on "Services," find the "Print Spooler" service, right-click on it, and select "Restart."

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