Well, tomorrow I'll be pulling the toilet out. Went to winterize today and everything was fine until I tired to flush the toilet. No water coming out. There was "pink" up to the water valve and the flush pedal operated, and the seal held water in the bowl, but something's broken. So, it goes to my shop in the Am to find out what? Yay me
Did you pull the line off the flush valve and look for crud?
There is typically a 'filter/screen' inside where the line goes on.
Often times holding your cell phone in tight spaces will allow you to see back in where your head wont fit.
The screen is cleanable with a little compressed air.
Just a note. 5picker is correct but if water will not pass through neither will compressed air. Typically the cleanout (without pulling the valve) can be done with a toothpick or similar working the crud back out the water connection. The screen is not removable it is an integral plastic screen. Be sure and relieve pressure by turning off water supply and opening a faucet or two (cold side). Paper towels should be sufficient to mop up excess at the valve site. This procedure is predicated upon your toilet being a Dometic model 300 (310/320) series toilet. Just speaking from experience with this issue.
I meant (and should have specified) to pull the supply line and clean the screen from the supply side with a little compressed air. I've successfully done that without blowing it further into the screen.