My Lenovo laptop has both SSD (for OS) & HDD, suddenly the hdd has disappeared from computer, device manager, disk management etc. Sometimes its serial number seems to be visible in bios menu but sometimes it doesn't. Also when booting seems there is a small beep sound at 2 sec interval
Re-seat it and check again.
When detected, run CrystalDiskInfo app on Windows to check the Health
Most likely it's a sign of failing HDD.
In some cases if HDD is underpowered it might give a tick sound, but generally beep or a click or a tick sound from HDD means it's about to fail.
Take backups immediately if data is important, (whenever detected) or see if it gets detected thru external USB 3.0 casing.
FYI here is how it sounds (place ears closely to speaker or use headphone) drive.google.com/file/d/1Bkofiz0zKRAoQ8VuY74Lx1iYJt5SAXBG/view?usp=drivesdk
