Moving tunes into i-tunes library from music file

[Dragons Claws]

Hopefully an easy one for someone. I saved my i-tunes to an externl drive, for some reason the library is now empty and all the songs I had have gone into the I-tunes music file. I have moved some over back to the i-tunes library but it is only letting me do it one album at a time which i taking forever. How do I move them en-masse into the itunes library and how do I make sure that all the ones that I had bought have the password entered to activate them again without me having to hunt them out manually?