I bought the new laptop inspiron 3593 but already have this annoying bluetooth disappear from device manager and no switch button for bluetooth....searching the net i found majority have this issue specially those who have qca9377 in particular

I did everyhting in the net solution since it is not a dell laptop issue . It could be driver or windows problem. 

For those who is having this annoying issue specially dell laptop users like me.
I have gotten a strong solution that requires no restart provided you have the correct driver installed
My bluetooth adpater brand QCA9377 which most are having this USB descriptor issue and bluetooth icon missing. I am using Inspiron.

This solution is might not be permament because the problem might come back but it is pretty much a driver issue i think But at least you dont have to restart which take time (if no ssd user)

OKA easy steps.

1.Go to the device manager
2.Click the double Usb Serial Bus controllers at the bottom (or just one click the arrow at left)
3.Now you should see the device descriptor failed device with caution mark. Right click and click DISABLE.
4.Then right click the " intel usb 3.0/3.1 extensible host controller" and uninstall it.
5. use your trackpad to go to action menu at the top and click "scan for hardware changes"
your bluetooth icon should reappear and the failed device should be gone. At least for the moment

Step 2 must be done and that is disable it ..if you uninstall without disabling it at least didn't work me for me... I have just tested before posting or commenting this.

it is still issue for dell user as disabling and doing further steps like this does not give us flawless experience. It is a wide issue.