Hi @amitgandhi95125
The coin cell RTC battery (Real Time Clock) connected to the motherboard has failed and needs to be replaced.
This battery maintains the time and date and all the BIOS settings when the laptop is turned off. It is a non rechargeable Lithium coin cell battery and usually lasts for 4-5 years
Here's the [http://www.hp.com/ctg/Manual/c01531211.pdf|maintenance and service guide] for the laptop.
Go to p.50 to view the procedure to remove/replace the RTC battery
Search online for ''486835-001'' to find battery suppliers that suit you best.