File name problem(?)

Your initial mv renamed the file to a name containing a newline at the end. You forgot to close the quoted string of the new name and pressed Enter. After pressing Enter (inserting a newline), you closed the double quote. This inserted a newline into the filename.

To rename the file, use

mv $'Powerwolf - Resurrection by Errection.mp3 \n' 'Powerwolf - Resurrection by Errection.mp3'

Note the space before the \n. It looks like this should be there according to the ls output.

You could also use a * to match the end of the name with a newline:

mv "Powerwolf - Resurrection by Errection.mp3"* "Powerwolf - Resurrection by Errection.mp3"