My Macbook Pro is not reading the OS.

It's been for already 3 hours that is trying to read the OS(I can only see the screen with the apple ion and a weel charging). This hapened when i finished installing Mavericks The instalation guide asked me to restart the device and when i Restarted This happened i thought it was part of the installation but i don't think this is normal.

Everything is okay the computar has less than a year and i was running Mountain Lion before (10.8).

What can i do? Does anyone have an idea what is hapening?

Thank you

btw, sorry for my english, i'm from spain.