HP Envy 7640 Printer Offline
Check if the printer is turned on and linked to the same wireless network. Choose Start -> Settings -> Devices -> HP Envy 7640 Printers & Scanners. Check if the device is present. If so, right click on it, select Use HP Envy 7640 Printer Offline to uncheck the box. Check if the router is providing a stable internet connection. Also, disable and enable the HP Envy 7640 Wi-Fi feature of your computer.