If you are implying that: 'I accidentally left it at home' You should say se me olvidó mi cartera, in this case, cartera is the subject, in which case, the responsibility is shifted to the cartera itself. This is a very useful expression. "Anoche, yo corté mi dedo" OR "Anoche, se me cortó mi dedo" These two sentences are different, The 1st one means you cut your figure,while the second means your figure was cut,probably by others, if so, they should be held responsible for it. I hope you can get their difference now. Good luck.

Se me ha olvidado la cartera/he olvidado la carteta/olvidé la cartera. ---> All of them are right. Anoche ME corté el dedo "Anoche se me corto mi dedo" is not right because your finger doesn't cut itself, you are the one who cut it, although it's not purposefully.

Yo olvidé mi cartera is right, and we usually take the 'Yo' for this kind of sentences, which is also right, we just say: Olvide mi cartera. Se me olvido mi cartera is not quite correct, we say: Se me olvido -la- cartera. Again, 'Anoche, yo corté mi dedo', could be 'Anoche corte mi dedo'. And 'Anoche se me corto mi dedo' is not correct. REF.: I'm a Certified Spanish Teacher.