It happened to me once. I slipped as I got into the bathtub (we didn't have showers way back when..just tubs to bathe in) and hit my side on the edge of the tub. I was maybe 10? It knocked the breath out of me and I still recall the terror of being unable to breathe...I couldn't catch my breath. I thought I was dying. I don't know how long it lasted but I couldn't even call out to my mom. Many years later I had a slight brush with what I guess was a sort of asthma. It only lasted about 3 months and it was very unpleasant but I got over it. Otherwise I've not had any problem with it. If you ever did experience being unable to breathe what caused it and how long did it last and did it ever recur?
When I was around 35, I accidently punched myself in the throat while taking a shower. I was washing, my hair, when my hand slipped, bounced off the wall and “bam!” – right in the throat (hard). I tried desperately to suck in air, but nothing. Not even a gasp. Utterly terrified (and in pain), I ran around the house desperate trying to breathe as thousands of things flashed through my mind. For some strange reason I recalled that the way to stop choking is to sit down and put your head between your legs. So I did. Sure enough, my throat began to open. Let me tell you, air never tasted so good!!
I know now that stress makes the body tighten up. My hysteria was making things worse. Calming myself down like that allowed my throat to relax, thus letting me breathe.