Whenever the Hard Disk Short/Long DST test fails that indicates that the Hard Disk Drive has failed and that requires a replacement to resolve the issue
HP will provide a replacement Hard Disk Drive if the Notebook warranty is Active, If not you need buy a SATA Hard Disk Drive from a retail shop nearby
Please Contact HP if your HP Notebook is under warranty, HP would replace the Hard Disk Drive and provide you a Recovery media to restore factory operating system after replacement (if you've not yet created Recovery Discs/USB Media)
Note: Back up all the personal data to an external drive if it's possible. Otherwise you could connect the failed HDD via SATA to USB adapter with another PC or same PC after replacement of HDD & re-installation of OS and try copying /recovering the files. You can also refer to the below shown link for further support
I have checked with service center technicians on hard drive replacement. They informed that they can replace the hard drive and install the drivers only but not the original windows 10 OS , it is costly to buy again. Any way to get the original Windows 10 OS from the HP recovery or HP team can help me to get my original OS product key?