@mohit98
This most likely means the contacts have become worn for the power button and this would require that to be replaced -- which can be very expensive because the laptop has to be completely disassembled in the process.
We are not able, or permitted, to provide any repair estimates or equipment prices.
For this information, you would need to contact an HP Repair or Service Center.
Since you live outside the U.S., here is a link to HP Service Centers, by Country/Region: https://support.hp.com/us-en/service-center
If that link does not provide you sufficient information, then use the main HP link:
https://support.hp.com/us-en/contact-hp?openCLC=true
I've found those links to be unreliable if you're using Win10 and the new Edge Browser; so if you are, you need to use something else, like FireFox.
Good Luck
I am a volunteer and I do not work for, nor represent, HP