SSL certificate

Hi

I was trying to check if my hosting service includes SSL certificate, and changed http by https in General Settings… After safe this change, my website go down (meditaser.com) and I can′t even see the wp dashboard to revert the change. Everything is showing error 404 – page not found
I know this is not an error of the Theme, but I really appreciate if you can help me to fix this big issue… I don′t know how to fix it.

Thanks in advance

Claudia