I see that your HP Pavilion Desktop PC is not booting up.
Let’s begin with a Hard Reset.
To perform a hard reset, use the following steps: 1) Disconnect all external devices connected to the computer - USB devices, external displays, printers, etc. 2) Unplug the Power Cables from the computer. 3) Press and hold down the power button for about 15 seconds to drain any residual electrical charge from the capacitors that protect the memory. 4) Re-connect all the Power Cables and try to Power on the computer.