Hey, welcome to the forums. There’s a bunch of moving parts when we are talking about the WiFi, so you will probably have to get it plugged in with an ethernet cable, to get SSH access, and investigate what is going on.
I’ve ran in to some problems with the MODEP WiFi and upgrades in the past (though that should be resolved now), and I wrote up a thing with some info and troubleshooting ideas: MODEP, Pisound, WiFi, and You
Without at least some access to the system to poke at what’s wrong, there’s not a good way to tell what’s happened to your WiFi.