Hopefully you kept a copy of your library before you corrupted it. You want the remap folders command from the File>Advanced.
i copied everything the way i wanted it to be on my new drive. opened musicbee located the moved library .mbl and tried to remap it.
the old path was : F:\Eigene Musik\Musicbee\Music\Musicbee\Music\ <songs...>
in musicbee the remap option said: map music file path from from: "F:\Eigene Musik\"
to the new path: "F:\Musik\"
Right in the directory in the root path is the music.
Doesn't work for me :/