Start with the right checks.
A charged headset can still be connected to a different device. First distinguish discovering the headphones, pairing them and selecting them for sound. Each is a separate step.
What to do next.
Charge the headphones and follow the manufacturer’s pairing instructions. Move them close to the PC.
Open Settings, Bluetooth & devices and confirm Bluetooth is on.
Choose Add device, then Bluetooth, and select the intended headphones when they appear. Check the exact device name.
If pairing succeeds, choose the headphones in the application’s audio settings. Check whether they are already being used by a phone or another computer.
Check the result.
Play ordinary audio and make a private test call. Confirm both listening and speaking, because a playback connection alone does not prove the microphone works.
Stop and get help if…
The device never appears, repeatedly disconnects or only one application fails. Record the model and the stage that fails before removing drivers or buying replacement hardware.