Mod wouldn't work and my attempts at fixing didn't work

So, I only recently got MCreator for another time, and I wanted to make 1.12.2 mods. I tried to make an item but it kept telling my that something was wrong in the code or something. Thats only one of the two problems I've had. I also thought that maybe reopening it would work but I couldn't and thus had to reinstall it, but That didn't work either. There is no app anywhere on my computer. I don't know if its a problem with the fact that I have 1.9.1 (Which I don't know if its the latest version or not, probably not) so I'm about to try that but Idk if that'll work. I kindly request some help.