[Question] I can't open my game

I was making a regirock encounter event in my game on pokemon essentials and when I saw everything was working fine I closed my game, but now whenever I try to open my game now it comes up with an error which says

"FILE DATA/species.dat not found"

I tried deleting the event and I tried recompiling the files by holding control while pressing the playtest button but I got the same error. I was wondering if I was recompiling my files wrong or what to do about this error.