I suggest you update you BIOS to the most current version available from Gigabyte. If you are running the most recent version, re-flash it just to make sure it is loaded properly.
Next, I would enable SMART in the BIOS and see if it is indicating any issues with your HDD. If so, it may be time to look at a new HDD.
Thanks COLGeek, for your support. HDD is not showing at BIOS for the first time entering. But on restarting it is working and getting recognized in BIOS.
My HDD already exchanged 2 times. As it is a repaired HDD therefore I suspect it more.
I shall try to do what u have recommended.