So you’re trying to do a video phone call to a friend on Messenger and you cannot hear them but they can hear you. They shrug their shoulders and mouth various words - usually swear ones! They shrug their shoulders again and you both try very hard to find out what has gone wrong.
Previously they phoned another friend and all worked well but suddenly the computer is not playing ball. They’ve looked at all the apps and buttons and controls. They’ve checked sound and everything seems to be okay but still they cannot hear you.
They phone another friend to see if is just you but the same thing happens. At a loss as to what to do about it they take their laptop to the shop to get it fixed and worry about how much it is going to cost them.
The man in the shop presses F1 or F6 or 7 or 8 and hey presto the sound is perfect! No fees charged but he tells you to keep your kitten or puppy away from your laptop as it has probably sat on it!
You go back home feeling rather embarrassed but thrilled to bits to have found the cure. You make a mental note to check the laptop after the critters have been sitting or laying on it!