404 when trying to access

Hi, I lost access to my website. When I try to log in as an admin or edit posts, this is what I get:

404 Not Found
The request /wp-login.php?redirect_to=http%3A%2F%2Fspoldzielniaposilkowa.pl%2Fwp-admin%2F&reauth=1 was not found on this server.

HELP!