First, did you back up your site before trying to upgrade?
Did you upload the files via FTP/SFTP individually, or did you upload the zip archive, extract it on the server and move the files into place?
Check a phpinfo() and see if allow_url_fopen is set to On. If it is, put the
installer.php file from here in your site root and run it from the browser. This file automatically fetches the MODX zip file and extracts it in place, then redirects to the MODX setup.
You'll need to edit it to download the 2.2.14 version instead of 2.2.13. Line 38 (for standard installation):
'revo2.2.14-pl' => array(
'tree' => 'Revolution',
'name' => 'MODX Revolution 2.2.14-pl Standard Traditional (04.04.2014)',
'link' => 'http://modx.com/download/direct/modx-2.2.14-pl.zip',
'location' =>'setup/index.php'
),