iTunes does not recognize folder structure when importing music I have imported a lot of Music into iTunes in a folder structure:
&lt;Artist&gt;/&lt;Album&gt;/&lt;Song&gt;. Unfortunately iTunes has not recognized these information, so that now I just have a lot of songs without artist or album information. (Actually I think that these has always worked until now). 
Do you have any idea what went wrong here and what I could do, to get this information into iTunes (and the iCloud)?
Doug's AppleScripts for iTunes are a good place to start looking for any iTunes scripting solutions.
In your case Tags Mirror Artist-Album-Filename looks very promising:

This script copies the names of the Artist folder, Album folder and filename (minus its extension) of the selected tracks' file paths to each corresponding track's artist, album and song name tags, respectively.
For best results your files and folders should be arranged in this format:
Artist folder / Album folder / filename.xxx