Hi @sparky95
Check if BT has been enabled in BIOS.
Start the laptop and press F1 when the Lenovo logo is displayed on the screen, before it boots into the OS.
When in BIOS go to ''Security > I/O Port Access > Bluetooth''.
If it is disabled, enable it, save the changes and restart the laptop. It should now show in Device Manager etc.
Here's the [https://download.lenovo.com/pccbbs/mobiles_pdf/t480s_ug_en.pdf|user manual] for the laptop. On p.72-73 it shows all the different hardware components that can be disabled in BIOS under the I/O Port Access sub menu
''If it was already enabled in BIOS'' but it wasn't showing in Device Manager (did you check "Other Devices" category and also View > Show Hidden Devices in DM as well?) then perhaps it is a faulty WLAN/BT card. Is the WiFi working OK?
Here's the [https://download.lenovo.com/pccbbs/mobiles_pdf/t480s-hmm_en.pdf|hardware maintenance manual] for the laptop. Go to p.69 to view the necessary pre-requisite steps and then the procedure to remove/replace the ''WLAN'' card. Check the make and model information on the card and use that information to find suppliers of a replacement card.