@davidjones68 Do you know if you have Killer Wireless and Bluetooth or Qualcomm Wireless and Bluetooth? If you don't know you may have to go to https://www.dell.com/support/home/en-us and put in your Service Tag then click on the link 'View product specs' in 'Quick links' on the right. After you know which adapter you have, try downloading and installing the Dell driver for that adapter. 

Here is a link to a thread with a problem similar to yours:

https://www.dell.com/community/XPS-Desktops/XPS-8930-bluetooth-disappeared/m-p/7526356

The same thing happens about once every couple months on my xps 8930. The only way I can get bt back is to shut down the pc, remove the power cord, and after 30 seconds, plug power back in and start the pc. 

It's Killer and I have updated all the drivers.

@lem1 Your fix was mentioned as one of the solutions in the link I posted.

@davidjones68  Open Device Manager and click View>Show hidden...

Now look through all DM entries and if you find an "Unknown" device listed, right-click and uninstall it. Then click Action>Scan for hardware changes. Now see if BT magically reappears in DM. Then reboot and confirm that BT is still listed in DM...

Repair this "C:\Users\cscla\Desktop\Dell Drivers\Intel-Serial-IO-Driver_3MK53_WIN_30.100.2020.7_A06_06.EXE"

Should fix the issue

Download from the Dell website.