I understand that you are missing a couple of songs from your music library that you purchased and when you went to download them again, it is stating that you need to purchase the songs again. Being able to have access to all of the music that you've purchased is important. I'll be happy to help.
What you will want to do is to download your past purchases. The following article goes over the steps needed to complete this.
Redownload apps, music, movies, TV shows, and books from the iTunes Store, iBooks Store, and App Store
On an iPhone, iPad, or iPod touch
- Open the iTunes Store app.
- On your iPhone or iPod, tap More > Purchased at the bottom of the screen. On an iPad, just tap Purchased.
- Depending on what you want to redownload, tap Music, Movies, or TV Shows, then tap "Not on This [device]."
- Find the movie, TV show, or music that you want to redownload, then tap it.
- Tap to the right of the title. The movie, TV show, or music downloads to your device. You can find movies and TV shows that you redownload in the TV app3 or Videos app, and music in the Music app.
Have a great weekend!