网站和WP后台无法打开，咨询过bluehost客服还是没有解决

网站和WP后台都无法打开，显示“Access denied for user 'root'@'localhost' (using password: NO)”，咨询过bluehost客服，得到如下回复：

Gagana
I have tried to change the database user name, but it still didnt work out. Looks like your website is trying to use root access to databse.

Gagana
You might need to contact a developer for this.

Gagana
Somewhere your database is trying to use root as username name, which is incorrect, you will need to find where and use the correct username as shows in config file.

由于是技术小白，实在不明白是什么意思，恳请大神指教，不胜感激！