DB Error with Download manager

If you click on any of them dl links on my site for eg

https://liberta.espoireve.com/?dl=bubblessmilies.zip

I’ll get this error, it worked before but just stop working today, no idea why though..

WordPress database error: [Unknown column ‘user_level’ in ‘field list’]
SELECT user_level FROM wp_users WHERE user_login = ‘admin’

Warning: Cannot modify header information – headers already sent by (output started at /home/huaian/public_html/liberta/wordpress/wp-includes/wp-db.php:102) in /home/huaian/public_html/liberta/wordpress/wp-content/plugins/download-mgr.php on line 400

Warning: Cannot modify header information – headers already sent by (output started at /home/huaian/public_html/liberta/wordpress/wp-includes/wp-db.php:102) in /home/huaian/public_html/liberta/wordpress/wp-content/plugins/download-mgr.php on line 401

Warning: Cannot modify header information – headers already sent by (output started at /home/huaian/public_html/liberta/wordpress/wp-includes/wp-db.php:102) in /home/huaian/public_html/liberta/wordpress/wp-content/plugins/download-mgr.php on line 402

Warning: Cannot modify header information – headers already sent by (output started at /home/huaian/public_html/liberta/wordpress/wp-includes/wp-db.php:102) in /home/huaian/public_html/liberta/wordpress/wp-content/plugins/download-mgr.php on line 403

Warning: Cannot modify header information – headers already sent by (output started at /home/huaian/public_html/liberta/wordpress/wp-includes/wp-db.php:102) in /home/huaian/public_html/liberta/wordpress/wp-content/plugins/download-mgr.php on line 404

And a lot of weird characters

Any idea how to fix that?

Would appreciate any help ??

I also happen to need a lot of help for editting my htacess

Thank you ??