Permalinks not changing from Post Name to Custom Structure /%postname%/

My permalinks are not changing from post name to custom structure /%postname%/, though after clicking save changes I am getting a message “permalink structure updated” but it is still the same. I am using Tesseract Theme by Tyler Moore and have tried various means to resolve the problem. I deactivated all my plugins still it didn’t work.
Since I have no idea about coding here’s my .htaccess file

# 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