I do computer repairs for a living and once I had this totally insane problem. Someone's speakers wouldn't work. The PC was located one of those huge cover-the-whole-backside desks against the wall, so I sat down in the dark corner and booted up the PC. I checked if the cable was plugged in, so I reached behind the desk, found the cable by touch and it was indeed plugged in correctly.
Then for two hours I've tried:
* Toying with volume.
* Drivers.
* BIOS.
* Using a headphone in the front jackets (those worked)
I got desperate and threw the volume to 100% and when I sighed I was certain I heard music from one of the drawers. Turned out the cables I had found behind the desk were not the speakers, as one would assume, those were hanging next to the ones of the headphone in the drawer, which was actually connected.
Or better, on my business phone:
"Hello, Rami Ismail, Computer repairs and Graphics Design."
"Hello, with [forgot name]. My PC doesn't work." (Crap. Not one of those.)
"Okay, so, what exactly is the problem."
"The PC doesn't start up. It goes to that Windows screen and then restarts." (Oh dear...)
"What Windows do you have?"
"The one that came with my PC."
Sigh...
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