Bluetooth not available after icloud keychain window popped up

My Mac Pro is not usable now. After using a couple of hours sitting with the screensaver on, I returned to find my wireless Apple mouse not working (cursor frozen), and an iCloud Keychain pop up window reading, "A new iCloud Security Code must be created". I noticed that the Status Bar Bluetooth symbol showed a jagged line through it indicating it was not available. Not knowing how to fix, I thought of rebooting but could not navigate to the pull-down menus using keyboard shortcut Control F2.

I shut the computer off by holding down the power button for a few seconds. I then turned back on -- same exact situation. Using my Macbook Pro, I found an Apple discussions article that said to fix by disconnecting all USB devices and starting again. Still, no luck. Same situation

I turned the MP off, plugged in an old wired Apple mouse, restarted, still, even wired mouse did not work.

I found this article which said to trash Bluetooth preferences.

http://osxdaily.com/2014/02/17/fix-bluetooth-not-available-error-mac/

I haven't applied this fix yet, as I would be entering into areas with my limited technical skill that I am not totally comfortable addressing, though it looks fairly straight forward. [My fear of performing these operations is that I make the situation worse]

Any suggestions on what to do? Somehow I feel that the iCloud Keychain Security Code alert caused this, though that is just a hunch, as that window has been ever-present every time the computer was restarted.

Hoping for a fix that I can handle. Thanks ~