Nothing found for Wp-admin, .htaccess problem?

Dear people,

I’m having an issue with my WordPress installation on the domain http://www.vlodonline.nl
When I go to http://www.vlodonline.nl/wp-admin I DON’T get the logon screen, but instead my browser is showing a screen that says that ‘nothing is found for wp-admin’

I searched everywhere but I can’t find a solution. In the beginning I was able to normally login and I don’t know or remember what I have done to disturb things.
Maybe this is an .htaccess problem?
At the moment, I have 2 .htacces files with both the same content.
1 in in the folder ABOVE the /wordpress/ folder
the other one is directly in the /wordpress/ folder.

When I remover the one in the folder ABOVE the WordPress folder, I get a 404 error.

The content of the .htaccess files is:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress
—–
Any suggestions are most welcome