Ah, ok. You have the same problem as here. I’ll quote my response here in case you have questions, so that we can keep this on topic for your issue:
ExpressionEngine, pre-1.6.4, used to chmod all uploaded files to 777. This is because years ago, it was fairly common to see servers configured so that files uploaded via PHP would be set with the server’s default permissions, as opposed to inheriting the user or folder’s permissions. The result of inheriting server permissions is what you see here - they become unreadable by the public and can even prevent the user (you) from modifying the via FTP.
In 1.6.4, which was a security release, this code was removed for security reasons, and because the majority of web hosts these days have it set for files uploaded by PHP to inherit from the user or folder’s permissions - which results in readable files.
So, in brief - at this point you will need to put in a ticket with your host explaining that files uploaded by PHP do not have public read permissions, and ask them to change this.