Q: Grayed out songs

Various reasons. Is there a dotted circle next to them? Did you synch them over?

You purchased them directly from the iPhone then? Can you resume your pending downloads?

iTunes: How to resume interrupted iTunes Store downloads

          http://support.apple.com/kb/HT1725

If there is nothing to resume, swope to delete and grab them this way:

Downloading past purchases from the App Store, iBookstore, and iTunes Store

          http://support.apple.com/kb/HT2519

Lets be clear here. You downloaded them into iTunes on your computer, then brought them over to your device?

what did you do?