My songs are in my library but won't sync over to my iPod nano. Why?

Step 1: To Delete the songs you don't like from iTunes library: Launch iTunes > Click Music mark > Select My Music > List your music as Songs > Select the songs you don't like > Click Delete to remove them. Step 2: Connect your iPod to computer > Sync the music from your computer to iPod with iTunes

How Do I Download Songs Onto My iPod Nano?
IPod Nanos are portable multimedia players that allow you to playback songs and other content (e.g. video) no matter where you go. They come in a variety of memory sizes such as 4GB or 16GB (gigabytes) and work with iTunes to upload songs. ITunes is the iPod default management program which allows you to upload songs to its library, create playlists and sync music on your iPod quickly and easily. This simple process will have you jamming to your favorite songs in no time.


Downloading to an iPod Nano1Connect your iPod Nano to the computer using the USB cable. Launch iTunes if does not automatically launch. When you launch iTunes, it will display your iPod Nano on the left panel.
2Add music to your iTunes library. Click the "File" button on the top menu and click "Add to Library." Locate the song you want to upload to your player and click "Open" to load it to your program.
3Click the "+" button on the lower left panel to create a playlist. Type a name for the playlist and drag the uploaded file to it. To upload additional songs, repeat Step 2 and drag the uploaded additional songs to the created playlist.
4Drag the songs in the playlist up or down to select the order in which the songs will play.
5Sync your iPod Nano. Click the iPod icon on the left panel after importing songs and adding them to the created playlist. Click the "Music" tab and click "Sync music." Click "Select playlists, artists and genres" and select the playlist you created that contains the songs you want to upload. Click "Apply" to automatically sync and download the songs to your iPod Nano.
6Click the "Eject" button and disconnect your iPod from the computer.

Tips & Warnings
Click "Music Store" if you want to purchase a music file. Search for the song on the iTunes store and download it to the iTunes library.

Connect your iPod to your computer with the USB cable that came with your iPod. The iPod screen should say "Do not disconnect".

Your iPod should appear under Devices in the bar to the left.

Decide whether you want to sync your iPod with your iTunes library or manually put songs on your iPod.(nano only)

Syncing your iPod will automatically add all of the songs in your library to your iPod. It will also delete any songs from your iPod that are not in your library. Click on your iPod icon and select Sync in the lower right corner.

If you do not want all the songs in your library on your iPod, make a playlist of all the songs you do want, or decide which playlists you want to include on your iPod.

Click on your iPod icon
On the top bar, click on the button which says "Music"

Make sure the box that says "Sync Music" is checked, then check the box for whether you want your iPod to sync with the entire library or selected playlists. If you click selected playlists, select the playlists you want in the playlists category. For newer iPods you can check which artists are included on your iPod to automatically import all the songs from each selected artist onto your iPod

I think you are trying to sync with a different library than your own original library that you synced your ipod before. OR the original songs that are in your ipod are no longer in your library. There is a option that you could sync songs manually.
1. Connect your iPod 2. Start iTunes 3. Click on your iPod 4. Check option that says Manually sync songs
Now you can sync your music without deleting the old songs. I hope

The following information has come directly from the apple support web site.

Adding Content Automatically or Manually
There are two ways to add content to iPod nano: ? Automatic syncing: When you connect iPod nano to your computer, iPod nano is automatically updated to match the items in your iTunes library. You can sync all your songs, playlists, videos, and podcasts, or, if your entire iTunes library doesn’t fit on iPod nano, you can sync only selected items. You can sync iPod nano automatically with only one computer at a time. ? Manually managing iPod nano: When you connect iPod nano, you can drag items individually to iPod nano and delete them individually from iPod nano. You can add songs from more than one computer without erasing songs from iPod nano. When you manage music yourself, you must always eject iPod nano from iTunes before you disconnect it.

The following URL will bring you to the iPod Nano manual. For more information on setting up you iPod see chapter 2: Setting up iPod Nano

http://manuals.info.apple.com/en_US/iPod_nano_5th_gen_UserGuide.pdf

I hope that information above has helped is some way.
If possible please rate this solution.

You have to delete songs using itunes.

if you delete from itunes library it will delete it from ipod
if you only want certain things on you ipod then sync to a playlist you create or sync only checked songs .

hey in the ipod music section in itunes put it as add sync all music and play lists

If I were you i would look in your song library, even though they are no longer on your mp3 player, they are very likely here.

Look to the far left of the windows media player sync page, here you will see a list of catergories including
"Playlists"
"Library"
"Media player"
"media player"
"Ipod"(or something like that)
And subcatergories. Go up to
"library"
on the list and click you should find your songs here.

If they are not there, then look in the recyclebin.

I hope I could be of assistance. Have a nice day! =D

Start with these five simple solutions: Reset, retry, restart, reinstall, or restore
http://www.apple.com/support/ipod/five_rs/

Your iPod syncs the songs in your iTunes library every time you plug it into your computer, adding/removing songs is only a matter of adding/deleting them from your library and re-syncing your iPod.