Install error – Can´t login – HTaccess

Hi Guys,

The same login problem in that it redirects to a 404 for the login page again and again and the site itself returns a 404. Site is the-united-nations.org

I have:

Logged out
Cleared cache / cookies
Changed values in phpmyadmin
Tried the plugin renaming
Deleted htaccess
Commented two lines in config.php

The closest all this has got me is that when I deleted the htaccess everything functions…. except the other sites I have on the same hosting which need the htaccess. I have tried setting up bith a redirect for the United nations site but that just produces a 500 error.

Its been a very long afternoon and I´m wondering if:

There is a definitive solution to this?

OR

IF there is an oloder “stable” version that I could use that doesn´t present these problems.?

Any help is most appreciated.