The only way I could try to dig my way out of this mess was to:
b) use my slow-as-molasses smart phone to look it up
c) call K at work and beg him to help me
In the end, the right keywords to search were "control key stuck" and the right action to take (for me) was to hold down both Ctrl buttons at the same time. I'm so elated, I'm going to continue procrastinating more and post the solution right here for all to see:
I rarely say this, but thank God for the Internet!