Hi @airplanekiwi
Check in BIOS to see if the BT adapter has been disabled.
To get to BIOS, turn on the laptop and press F2 a few times to get there. The [https://download.lenovo.com/consumer/mobiles_pub/c740_14iml_15iml_ug_en_201908.pdf|user guide] (see p.28) shows how as well.
When in BIOS scroll through the menus to see if it is listed.
Unfortunately the user manual doesn't mention anything about it but maybe check the Configuration settings and it may be in there.