General help

Please see the upgrade FAQs for upgrading from 1.9.  I would recommend setting up a copy of your site on a test server and upgrading that before trying on your production site.  Be sure to have backups of the database and files before you begin.

Ricardo, thats a big Gap you are jumping.

First, you have to install Moodle 2.2 before even upgrading to 2.7, so it will be an immediate double upgrade, not just single jump from 1.9 to 2.7

Because server requirements have changed for Moodle 2.7 as compared to 1.9, so first thing you'll be doing is looking at the PHP, MySQL versions if they are good enough for your New moodle installation.

2nd, if you have plug-ins installed, best is to note them down and  look for the updated plug-ins available for Moodle 2.7, as sometimes Moodle installation goes OK, but outdated plug-ins that arent updated for latest Moodle versions bring loads of issues.

In any case, its ALWAYS recommended to create Backup copies of Moodle Database, Moodle Installation Folder and  Moodle Data Folder, just in case if something happens bad, you wont have issue returning back.

If, you can, create a replica of moodle site (depending on how Big your moodle is), and run it side by side upgrading the clone copy, if everything went ok, you can always change the paths. Are you on CPanel? hosting Moodle with a hosting provider or have home grown web server doing the job? 

If you are on CPanel, lemme know, I had created videos for someone at some point, showing them how to actually upgrade from Moodle 1.9 to moodle 2.2 and 2.7, I'll give you the link and you can download.