Just thought I'd let you know that I have solved this.  It seems that a recent driver update (CCleaner Pro) installed CSR Core Bluetooth 4.0  as the primary BT driver and this is apparently incompatible with Windows 10.  It wasn't showing up as a Bluetooth device in Device Driver, but eventually I found it under USB Controllers (helpful eh?) and rolled it back to "generic bluetooth device", it came alive instantly.
Hello Community, Apologies for this first-time post, I have lurked here for a while and found your advice and support a great help.  Now I have a problem I can't solve:I have an Optiplex 7010 running in i7 3770 and Win 10, nothing unconventional about it - apart from the fact that bluetooth has suddenly stopped working and although I can see the service is still running (via services.msc), nothing I can do will induce it to see my USB BT dongle.  I've checked the dongle itself is still OK (it is), but no matter what I do I cannot get it to load in device manager.  I've tried loading a separate driver for the device, that failed.  Any advice would be a huge help as I need bluetooth connectivity every day - this is a real problem.Thanks in advanceNE
Mysterious Bluetooth Problem - Advice Needed