First; weird url forward, now blank pages..

Hey Guys,

I have a problem with my website.
I was working on a theme, removing some lines in the header.php and thought it was working fine.
But then i tried to go to the admin part but i couldnt get there.
Wordpress forwarded me to somehwere else: Something like this https://outdoor-stevents.nl/login?redirect_to=http%3A%2F%2Foutdoor-stevents.nl%2Fwp-admin%2F
The link to the options page came out like this: https://outdoor-stevents.nl/login?redirect_to=http%3A%2F%2Foutdoor-stevents.nl%2Fwp-admin%2Fthemes.php%3Fpage%3Doptions.php

So i thought it might have something to do with the Cache (i have super cache plugin installed) But after i removed the cache folder the website turned completly blank…
So now i am not able to go to my website or get into wordpress..

The website is: https://outdoor-stevents.nl/
What ive done so far:
Removed the theme and uploaded the default theme, replaced all wordpress files except the wp-content folder, removed all plugins and looked online for a solution..

Nothing works :S

Hope one of you can help me..

Thanks, Daan