This happened two weeks ago today.
My trench wasn’t a big venue, but the second floor of an old storehouse, taking more or less 50 persons.
A woman I know should celebrate her 70th birthday, and had asked me to accompany the guests singing old songs for half an hour or so at the start of the party. She also planned 1-1 1/2 hours of dancing at the end of the party. Someone else was hired for this, but they suddenly told her that they couldn’t take the job, so she asked me if the trio I’m playing in could do the dance job.
Our guitar/bass player was occupied with another band that evening, so the female vocalist and I decided to take on the gig as a duo. With just three weeks to go before the job it was a lot of rehearsing and preparations to do this as a duo. We needed a lot of new songs that suited the audience, and we needed extra backing tracks on quite a few songs to fill in for the lack of bass/guitar/percussion. On top of this we didn’t have a mixer, so, for us to be able two use two mics while singing duets, I set up the solution Marty Wade describes in a post here on the forum, thus being able to use the mic inputs of my Focusrite 6i6 to do the vocal mixing and effects in GP. As you might understand, we was rather short on time 
The day for the gig arrived. We set up the equipment, tested the sound and set the volum level og my Bose Pro active speaker. Everything was ready for an uneventful evening
The vocalist left, and I played to the songs at the beginning of the party. Everything went as it should. I used one of the pianos from the TruePianos plugin, which I really like. I turned of my equipment, brought with me my laptop, and left for home until the dancing gig part of the evening. Our setup was at one end of the room, and I had already earlier asked the birthday lady if it would be safe to leave it there, which she of course thought it would be.
3 1/2 hours onwards and the vocalist and I was back and ready to play. I set up my laptop, turned on and connected everything and opened the gig file of the evening. NO SOUND AT ALL!!!
I turned on an off my Arturia Keylab Mk II 88, my Focusrite, closed GP and restarted the laptop. Still no sound.
Then this guy turned up. He was the father of this, maybe 12 year old, girl that had wanted to play some Grieg piece for her grandmother, the birthday lady. They thought my keyboard was an ordinary hardware keyboard and they had the audacity to try getting it to work while I was away. When asked, they might have tried to press both this and that. We are talking about the wheel selecting one of ten user configurations, and som buttons switching between different control banks. Trying out these didn’t help. During the search for the problem, the father, who maybe was not quite sober, although not so easy to see, tried to be “helpful”. He was holding up and twisting a little on my USB hub. I’m not sure, but I think that was when my laptop froze with GP open, and I had to do a hard restart. He also started to touch the preset volume of my Bose Pro. That was when I became rather rough in my voice.
Still no sound, and I went around to the backside of my gear. Then I saw the obvious reason for no sound. The cable that should go from the output of my soundcard wasn’t there. In their search for sound from the keyboard, they had just unplugged it and put it into one of the AUX contacts of the keyboard.
After having plugged the cable back where it belonged, everything worked, ALMOST. None of my used knobs and faders, apart from the transport buttons, had contact with their GP widgets, so I had to control them with the mousepad and arrows on my laptop, in a situation where it was so dark that I had to use the light on my phone to see what I was doing.
Musically, the gig went well, although we started maybe 20 minutes late. The guests where very satisfied with what they got.
In hindsight, it may well be that I caused the knobs and faders problem myself by cliking away from the right control bank, when the father said they might have tried those buttons. However, not my fault, since I really hasn’t used the buttons choosing banks up until this gig.
The positive thing coming from this experience; I have felt that I had a little to few knobs, faders and buttons to control all the widgets I wanted to control. I had forgotten about the three banks. Now, instead of having 9 of each of the mentioned control types, I suddenly have 27of each
This became a rather long rant I just had to tell someone that would understand my trials and tribulations. Thx for reading!
(I might make a post of it’s own about setting up those three control banks on my Arturia. Not totally straightforward, although easily solvable.)
