/wp-admin sends to endless redirect loop

I just started managing this website for a client a few days ago. yesterday i installed the yaost analytics plugin and updated 2 more plugins, one of them is contact form 7.
Now, when i try to log in to the wordpress admin page it says the page is in a redirect loop. The site itself is not running with the wordpress css and not letting me access any of the inner pages.
Can anyone help me?