Browser shows only index.html

I've uploaded all my files including HTML files and pictures. They are all
linked properly (I've checked it several times). SmartFTP shows me
that all files are online and after transferring I get a message that it's successfully done. So, I try to open my HP and it just loads index.html,
the other files are not available on the server although shown in smartFTP.
The funny thing is: when I rename a page (for example news.html) in
index.html it's loaded. I've experimented with folders (all files are normally in one folder), which led to a list of files, but the html files are
still inaccessible.

Why?
And how do I solve this problem? :?: