ProductKey clique aqui para descobrir o serial do windows! click here to discover the windows serial!
Para usuários da comunidade inglesa, espanhola, francesa e alemã, usarei o google tradutor!

My bluetooth suddenly disappeared from my Acer Swift 3 SF314-56G (CPU: i5-8265U, GPU: Nvidia MX250, RAM: 8GB) and its showing under "hidden devices" on Device manager.
I've tried:
Any ideas how to fix this? Thank you.
[Edited the thread to add model name to the title]
Reset BIOS or UEFI to default settings.
Try resetting the battery:
Try reinstalling windows:
If you have internet connection through Ethernet adapter, try pressing Fn+F2 buttons on your keyboard few times. It should physically re-enable your connection adapters.
Thank you for all the suggestions.
Reset BIOS to default settings, didn't work.
Downloaded the driver from the site with my SNID and installed the driver then restarted, didn't work.
Tried to press FN+F2 and turned on Airplane mode on and off, didn't work.
Tried resetting the battery and checking if bluetooth is ok, didn't work.
Reinstalling windows seems extreme and most of my settings and work is old. I don't think this'll fix it anyway as well.
May I please request any other solutions?
Maybe it helps to open the machine, remove the bluetooth adapter and delete the driver. Then reinstall the adapter, search for new hardware and reinstall the driver. It could also be that the adapter has a hardware defect, so that only a new one works properly.
Does the WiFi work well, or is it also flaky? Both functions are on the same card, so usually if it's a hardware issue with the card they both act up. Since it's showing under hidden devices that points to the underlying USB port that connects the Bluetooth hardware to the motherboard may be having issues. Sometimes doing as wascas suggests will clean the contacts a bit to recover from some slight corrosion. You can also see it with corrupted USB drivers so check in Device Manager to see if any USB hosts are acting up.
Thanks for the insight billsey, the Wi-Fi works well, I'm using it right now to post this and web pages load fine. I checked device manager and there was a device under USB controller that had the "!" mark sign:
That's it... Try deleting that entry then reboot and see if it's recognized when it reinstalls the drivers.