As you can’t get access to wp-config, try following these steps:
- Download the newest version of WordPress.
- Unpack it. Browse through the unpacked archive. Then delete the
“wp-content” folder. - Connect to your site via FTP.
- Head to the main WordPress root.
- Upload the new WordPress files. Overwrite all the previous files.
Now, go back to your site. You will find that the issue has been fixed.