Why did my letter c not work 15 minutes ago?

It could simply have been something wrong with your keyboard, like a sticking key or something.

Take the button off and then pop it back in, that’s what I do

I vote that there are some food bits under the keys. I clean my pc keyboard regularly by turning the laptop off, tilting it sideways, and blowing on the keys with compressed air. It’s amazing how much stuff flies out of there.

My c key stopped working once, too. Pop it out, blow on the insides and remove any gunk. That worked for me.

How old is the laptop? Keypads do wear out. When mine went south once, it was first evidenced by a “drifting” cursor on the monitor screen, even though my mouse was perfectly still and I wasn’t operating the joystick or touchpad. Later, as my keypad worsened (and I still didn’t understand what was wrong) my center keys stopped working: in particular, I, J and K started to fail frequently.

At that point I called IT support (it was a work machine), and a half-hour later I had a new and perfectly functioning keypad (the surface under the keys that the keys operate) installed.

Your issue may very well be a foreign object under the key. I’d try @LuckyGuy‘s recommendation as the fix that is least intrusive and least likely to cause damage. Removing keys can be a problem; I’ve seen the attachment parts break as that was attempted.