Sometimes when adding an album to iTunes not all of the songs are added. They missing songs ar added to my library as "Unknown Album". How can I move these songs to the correct album?

1. Select all of the songs that should have the same album.
2. From the menu bar at the top of your computer screen or at the top of the iTunes window, choose Edit > Get Info.
   If the message "Are you sure you want to edit information for multiple items?" appears, click Edit Items.
3. In the box next to "album," type the album name that you want all of the songs to have.
4. Click OK.

Are the 'Unknown Album' and 'Unknown Artist' songs WAV files?

iTunes doesn't seem to read any metadata on WAV files - if any even exists - so 01 Cool Song.mp3 works to get Example Artist on Example Album has track 1 be Cool Song while 01 Cool Song.wav gets Unknown Album by Unknown Artist has 01 Cool Song (with no track position).

Edit > Song Info and filling in Unknown Album and Unknown Artist for WAV files is necessary, and if you ever remove the file from iTunes, you get to repeat the process. I'd convert WAV to AIFF or another format and fix up any metadata that's missing.