wp-admin and wp-login.php redirect to Page Not Found

Hello,

I’ve seen tons of threads and websites talk about this issue but none of them has helped me.

A few months ago everything was working perfectly and suddenly I wasn’t able to get to the control panel as it always redirect to a page not found.

My wordpress installation has its own folder, so my domain is http://mydomain but internally it is http://mydomain/wp
I do have appropiate settings for ‘siteurl’ and ‘home’ values as everything works ok.

Now, when I try http://mydomain/wp-admin it redirects to mydomain/wp/wp-login.php which shows a “Page Not Found” error. This used to work in the past but not anymore.

I have tried everything described in this pages:
–http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory
–http://codex.wordpress.org/Changing_The_Site_URL
–https://codex.wordpress.org/Login_Trouble

Redards the last one, disabling plugins makes no difference (the only i hvae is akismet anti-spam). Also the theme I’ve been using is called ZenLite, but even changing the theme to twenty fourteen makes no difference. Btw, i had to change the theme from the database directly, since renaming the theme folder shows me nothing but a blank page. Even if I try to view the source and enable DEBUG mode it won’t show anything. Supposedly it should revert to the twenty something theme.

I’ve also tried updating wp-login.php manually but no luck.

Finally I tried adding

define('ADMIN_COOKIE_PATH', '/');
define('COOKIE_DOMAIN', '');
define('COOKIEPATH', '');
define('SITECOOKIEPATH', '');

to wp-config.php,but that didn’t work either.

I am out of ideas for now, so I kindly request for the community help.

Thank you.