Wrong album cover art

I am completely new to this so apologies. Using J River as a player I noticed a lot of my library songs had the wrong cover art, all the same in fact. I used mp3tag and this corrected a few but not all. How can I eliminate all of the incorrect art. Thanks in advance

Incorrect album art is usually caused by the player reading a folder.jpg file instead of the embedded art.

These folder.jpg files are hidden files so make sure you have the option "Show hidden files and folders" checked and the option "Hide protected operating system files" unchecked.

You probably have local cover-art-files and in addtition embedded covert-art in the tags of your songs.
In JRiver the location of your local cover-art-folder is configured in Options > File Location > Cover Art.

Habe a look how JRiver handles cover-art.
http://wiki.jriver.com/index.php/Cover_Art