Help with Impossible-to-remove music?

Ok, this is something really specific. I had a home made Music Album and I synchronized it with my iPod (5th Generation) and for a weird reason it was split in two parts. When I took a look to the Mac's iTunes and trying to fix it, it kept causing me trouble and in a moment of stupidity I took the album (finally in all gathered in 1 album, but with problems of song's order) to the trash and synchronized the iPod thinking it would also disappear. Instead, the song's names and duration appear in grey letters and I can't do anything with them. When I got the album back to iTunes and synchronized it again, the songs appear along with the grey ones in the iPod. It's so frustrating, what can I do?