I inherited a site from a previous developer, and we are setting up an automatic upload for my client's products. Last night, all of a sudden after uploading a former version of their site and a backup db, I began getting this error message:

A Database Error Occurred
Unable to select the specified database: ***_DB
Filename: /home/***/public_html/libraries/MX/Loader.php
Line Number: 104

The "Libraries" directory does not exist, and it does not exist on the old server (their old hosting account is still active). I have been looking online, and it hasn't really gotten me anywhere. Can anyone help me troubleshoot what could be causing this?

Thank you in advance for your help; your time and attention is very much appreciated.