Bluetooth doesn't appear in settings after reinstalling Windows

[thornowl]

Hello.

I'm using Pavilion 15-n253sr with Windows 8.1 64 bit. I have recently reinstalled Windows (same version as before) and found out that Bluetooth has disappeared from PC options and Control Panel. I have used it before, so I know my laptop supports Bluetooth. It's hidden in Device Manager, and is identified as Ralink Bluetooth PCIe adapter there.

I have tried:
- Installing drivers from the HP Support page here: https://support.hp.com/au-en/drivers/selfservice/swdetails/hp-pavilion-15-n200-notebook-pc-series/65...
- Using its hardware ID to look for drivers somewhere else on the Internet (lead to the exact same driver as above);

- Using HP Support Assistant's wireless check and Windows' automatic troubleshooting, neither have found any issues related to Bluetooth;

- Deleting the adapter in Device Manager and manually adding it back;
- Deleting the adapter in Device Manager and rebooting to let Windows add it back;

- Installing the driver again just in case;

- Switching Bluetooth Support Service from Manual to Automatic (there's no Bluetooth Service there, though);

- Editing the registry to change Windows version number from 6.3 to 6.2 as shown in a random Youtube video, because I'm that desperate.

Nothing worked, it's exactly the same as when I started. It still shows in Device Manager, though still hidden. And Bluetooth is still missing from settings and Control Panel.

Don't know if it's relevant, but I have a SM bus driver missing (couldn't find it on the Internet; hardware ID PCI\VEN_8086&DEV_0F12&SUBSYS_21DE103C&REV_0C ), and my F12 key (the WiFi switch) now always glows red as if airplane mode is enabled, though it's not. Switching airplane mode on and off doesn't fix that, and WiFi works completely fine despite that.