If Your Mac Won't Boot
One of the worst feelings in your technology life may just be the day when you press the power button on your Mac and nothing happens.
Now might be the time to run screaming through the streets, ripping your hair out by the handful. Or it may be time to go stand beside a window and stare pensively outside with your chest hitching and a single tear rolling down your cheek.
Nah, I'm kidding. Most of the time, this problem is solved pretty quickly, no hair-pulling or window-staring required.
The first thing to try is plugging in your power adapter. Yeah, I know, the computer was charged last night when you went to bed. But try it anyway, and make sure that the power cable is securely plugged in both to your machine and to the power brick. And also check that the brick is solidly in the wall outlet! Then give it a few minutes to see if anything happens.
If that doesn't work, you can try different ports on your machine, because if you've got a Mac with USB-C, you can use any port for power. Also, give a different outlet a shot. It's unlikely, but it's possible the problem has to do with your house, not your Mac!
If none of that does the trick, though, the best thing to try is what's called an SMC reset; the Apple support article on it lists several different methods depending on which Mac you have. If your computer was made in the last couple of years, it likely has a T2 chip, so you can give those instructions a go first (and if you want to figure out for sure, here's the article on that). If the steps don't work the first time, there's no harm in trying again.
This reset is pretty risk-free, and when I've dealt with Macs that won't start up, it works most of the time. And if it does, there's no need to stress about the health of your computer as long as it doesn't happen multiple times. So be calm! And step away from that window.