macbook air bluetooth won't connect

Can you provide details on the Bluetooth device you're having issues with?

One thing that comes to mind is that a lot of Bluetooth devices can only be connected to one device at a time. So, for example, if your device is connected via Bluetooth to your phone, it won't connect to your MacBook Air until you disconnect it from your phone. (Apple AirPods, AirPod Pros, etc. won't have this issue, as they can connect to more than one Apple device).

Try these steps to see if you can fix this issue

1. Make sure that your Bluetooth accessory and iOS or iPadOS device are close to each other.
2. Turn your Bluetooth accessory off and back on again.
3. Make sure that your Bluetooth accessory is on and fully charged or connected to power. If your accessory uses batteries, see if they need to be replaced.
4. If there's an app that you use with the Bluetooth accessory, go to Settings > Privacy & Security > Bluetooth on your iOS or iPadOS device, and make sure that you've turned on Bluetooth for the app.

If you say that bluetooth won't turn on, is bluetooth greyed out in settings? Then it is most likely a hardware issue

I am sitting right if front of my MacBook at with my bluetooth earphones on and the computer doesn't see any devises?

Did you figured out? i cannot see any new bt devices for last 3 weeks cannot figure out.. non of my apple devices..