1- Please check the error log detail of server.

2- Please upload all wordpress files again through FTP software.

Thanks
Mohammad

Do you mean download them, delete them on the server and upload again?

Thanks for your answer…

2- I was requested to upload the latest version WordPress again at your site.

Thanks
Mohammad

2. Go to the document directory of your website installation.

3. Make a backup of wp-config.php.

4. Open wp-config.php and insert or edit lines that control logging.

The following constant definitions need to be either added or edited in your wp-config.php file:

define(‘WP_DEBUG’, true);
define(‘WP_DEBUG_LOG’, true);

Most WordPress installations already have an entry for WP_DEBUG set to false so you’ll need to change this value to true. It’s not that common to have WP_DEBUG_LOG already set in the wp-config so most likely you’ll have to add that line.

After you’re done editing ensure that WP_DEBUG and WP_DEBUG_LOG are set to true and that each constant is only defined once in wp-config.php

Thanks
Mohammad