Im stuck on kingdom hearts?

i don't mean to sound stupid or anything and ive beat this game multiple times then ended up selling it cause i never played it. i finally got a brand new copy and i forget how to do everything! i'm completely stuck and i cant figure it out. i cleared traverse town and deep jungle. then i moved on to wonderland, and realized i couldn't do anything until i learned the green trinity because i cant open the door. so i went to the coliseum and i cant do anything until i learn the yellow trinity. so i looked up cheats and i saw that you cant learn the green trinity until you clear agrabah. but there's no path to get there and idk what to do. can i please have some advice? thanks:) id really appreciate it:)