[HELP] Website Corrupted

Hello,

After receiving errors with the newest version of W3 Total Cache in the Minify section as countless other users are, I disabled the Minify function. Then, I installed WP Minify to get the features back.

After this, I noticed that my website was no longer displaying any CSS layouts whatsoever, and I read that others users who encountered this reverted W3 Total Cache to an earlier version to fix it.

So I clicked on disable W3 Total Cache so I could downgrade, and suddenly I was met with a page that displays this message:

Warning: mysql_get_server_info(): supplied argument is not a valid MySQL-Link resource in /home/howtosin/public_html/wp-includes/wp-db.php on line 1567

Warning: Cannot modify header information – headers already sent by (output started at /home/howtosin/public_html/wp-includes/wp-db.php:1567) in /home/howtosin/public_html/wp-admin/install.php on line 54

I can no longer access any pages whatsoever on my website, and they all lead to the same page.

Please help. My website is https://how-to-sing.net

Thanks,
TheDJ