I actually have a similiar problem as described here:
A summary: I wanted to change the header height in the Twenty Eleven theme so I found I had to past some code in the functions.php. Doing so however gave an error which I couldn't fix. The error is found when you try to access the site: demeulenkamp.nl
Currently I cannot access my WordPress account anymore. Scanning the fora the only possible solution I found was pasting a new 'orginal' functions.php in the map using FTP. So I made an FTP-account in Cpanel and used Filezilla. The FTP connection seems to be working but unfortunately I only get to see an empty directory :(
Can anyone help me out? Thanks in advance.