If you take these lines out of .htaccess, you can login again. Also, rm -rf the hide login plugin directory. I’m pretty sure I followed the directions, and even tried it twice, but like others I got the 500 internal server error when I activated the plugin.
RewriteRule ^wp-admin$ %{REQUEST_URI}/ [R=301,L]
RewriteRule ^wp-admin/(.*?)$ /wp-admin/$1?%{QUERY_STRING} [QSA,L]
RewriteRule ^login/?$ /wp-login.php [QSA,L]
RewriteRule ^register/?$ /wp-login.php?action=register [QSA,L]
RewriteRule ^forgot/?$ /wp-login.php?action=lostpassword [QSA,L]
