garageband deleted when ios was updated on ipad

i had garageband and a handful of songs in it on my ipad. i made the stupid decision to update the ios (mostly so it would stop asking me to). i realized that the update deleted my garageband app and all my files along with it. i tried finding it today and it took me to the app store which said it now requires ios 13, which i don't have. i tried updating software again but it's still in the 12's. how do i get garageband back as well as my files? i am so livid i can't think straight. i feel like i was tricked by a thief who just threw my things away instead of at least trying to pawn them.