redirect problem, no login possible, site style/format is completly wrong

Hi there,

i can not log in wordpress site. (mrtngb.mr.funpic.de)

login in via
https://mrtngb.mr.funpic.de/wp-login.php
I am simply redirected to
https://mrtngb.mr.funpic.de/?p=all/wp-login.php

via
https://mrtngb.mr.funpic.de/wp-admin
i get redirected to
https://mrtngb.mr.funpic.de/?p=all%2Fwp-login.php&redirect_to=http%3A%2F%2Fmrtngb.mr.funpic.de%2Fwp-admin%2F&reauth=1

i already renamed my plugins folder to plugins-old (to avoid plugins-problems) and
deleted the .htaccess
with no visible changes in site behaviour.

any suggestions??

best regards!