You may already know there are (at least) two ways to confess your forgetfulness, both of which involve the verb olividarse.
It took me a long time to (more or less) get all this stuff straight. The simplest way to say you forgot something is...
Me olvidé - I forgot. Plain and simple isn't it?
There's also se me olvidó. So, which one do you use, and what's the difference?
My Spanish tutor tells me the differences are nothing more than geographical location and preference. Me olvidé (de) is used more in Central America while se me olvidó is used more in Mexico, South America, and Spain.
Today I'm only going to talk about me olvidé (de).
Here's some examples that will help you start confessing your forgetfulness.
Did you go to the bank? - No, me olvidé.
Me olvidé las llaves - I forgot the keys.
Me olvidé de traer las llaves - I forgot to bring the keys.
Hace mucho que me olvidé de él - I forgot about him a long ago.
Me olvidé de llamarte - I forgot to call you
Me olvidé del libro - I forgot the book.
You may have noticed some of the examples used "me olvidé" and some used "me olvidé de".
The way it's been explained to me, is that if you want to say you forgot to do something , you have to use "me olvidé (de)".
If you want to say you forgot something, you can say "me olvidé".
In a nutshell, that's it. If you're looking grammar explanations, forget it (¡olvídalo!), you'll have to look elsewhere for that.
Oh, antes de que se me olvide (before I forget), in my next post we'll continue this discussion, but focusing on se me olvidó, and then wrapping things up in third and final post, using the non-reflexive infinitive, olvidar.
***NOTE: There are 4 parts to this subject, and you can see them all by clicking here