404 error only on pages

For some time i got 404 error on all pages. Posts, photos, galleries, etc working good.
No changes in cofiguration.

I’ve found many advices that htaccess could be failed. But i’m sure there is nothing wrong here:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

I’ve also increased PHP memory_limit, disabled plugins. It not help.

I have no idea what else is wrong. Have anyone similar problems? Do you have any ideas?

Thank you in advance.