If you have not deleted the hidden recovery partition on the disk, follow the steps below.
Power on and right after press and hold the F11 key on your keyboard.
When you see System recovery message on the bottom left corner release the F11 key.
Select Troubleshoot then Recovery Manager (If you select Reset your PC it will perform a Windows reset)
On the HP Recovery Manager window select System Recovery.
You will have an option to back up your files, and you will need a storage media with enough space to back them up.
If you don't need to back up files, select Restore without backing up any files and click Next.
Read the summary and click Next again.
The process could take as long as a couple of hours on a mechanical HDD.
Once the process is done, click on Next and Finish buttons.
The laptop will reboot as it came from factory.