what a good writer you are becoming! This story has a small problem with tense. It happens in the past, but you are writing in the present. They must be the same. I will put it consistently into the present tense although stories are generally told in the past tense--thus the 'once upon a time.' You should try it again in the past tense.

A short story

Once upon a time there was a little girl who was is lost in a center of the Barcelona. She looks for her home. She was living in a small, old flat in fifth floor without elevator, with poorly painted walls and broke furniture.

When As she walks in the street, she meets a small rat that play is playing a Spanish guitar on the corner, and she asked asks it if heit  [pronoun must be consistent; it's either an 'it' or a 'he'] knows the where Cervantes Street is, but the rat didn’t know this streetdoesn't know. The rat tells her that if she wants to find this Street, she has to sing his song called “¿Ole ole? ¡Ole!” The little girl kept walking and continues to walk while singing “¿Ole ole? ¡Ole!” song.

She didn’t stop walking when she found a bifurcation. She asked themselves which was the right way to return her house… She comes to an intersection and asks herself which way she should turn to return to her house.