Reflexive verb help

[anitagringita]

Hi all, I just joined and started searching threads on reflexive verbs, but still have some questions.

I am confused when to use them! For example, I hear Spanish speakers use both se me olvidó and me olvidé when they forget something. I was taught to say things like me olvidó el libro and me torció el tobillo, but I am confused about the differences between the following:

se me olvidó/se me olvidé/me olvidó/me olvidé

me torció el tobillo/me torcí el tobillo

When do I need the se? when do the reflexive pronouns and the verb endings agree? and in general, when do I need a reflexive form. I hear it used in situations I didn´t realize it could be used.

(I realize this is a lot of teaching to do, so please feel free to comment on any part of it)

Thank you!