I made some modificaction on my item.php file (add OG fields, insert a FB comment box) I'm modifying the file located on html/com_k2/templates/default/item.php but the changes made to the files are not displayed on the front end.

Also I installed several spanish version of k2 but can not make it to translate the field labels sample "Written by", "Share this", etc. you can see sample in the following link: www.hoyamerica.com/peru/fao-aplaza-toma-de-posesion-de-nadine-heredia-como-directora

The correct path should be:
/templates/YOUR_TEMPLATE/html/com_k2/default.
More info can be found here:
www.joomlaworks.net/blog/item/194-k2-inheritance-sub-templating