My iPod won't add new songs or save playlists! Help???

You are creating the playlists in iTunes UNDER the iPod? If so, when you eject the iPod, they will obviously be gone from iTunes (since the iPod is not longer there). But are you saying that when you re-connect the iPod, and the iPod appears back in the iTunes sidebar, those playlists are not there?

It's quite possible that the iPod's hard drive volume has data corruption. You may be able to check and repair it, by setting it to Enable disk use (on the iPod's Summary tab) and using a disk maintenance utility on it (like it was a hard drive or flash drive). Do you use a Mac? If so, run Disk Utility. Select the iPod's hard drive volume in the sidebar (the volume is intented under the device), and go to the First Aid tab. Use Repair Disk. If there are errors, Disk Utility will identify them and attempt to repair them.

If there are data corruption errors that cannot be repaired, you will need to do a Restore on the iPod in iTunes. The Restore button is on the iPod's Summary tab. This will erase the iPod, re-install its software, and set it to default settings.

If you did not Manually manage music, my advice would be to do a Restore first and not bother with the checking for and trying to repair data corruption on the iPod's hard drive volume. As long as there is no hardware problem causing the data corruption, a Restore will probably resolve it (just as reformatting a hard drive and reinstalling everything often resolves data corruption issues on a computer). If you were using automatic syncing, you could then simply re-sync the iPod to get it back to the way it was before.

Unfortunately, while I sometimes use Windows, I'm not much of a "geek" when it comes to using Windows (like I am with a Mac). Maybe someone else will know how...

This is my suggestion, if you want to put in some work now to have a better long-term solution.

Connect the iPod so that it appears in the iTunes sidebar, under DEVICES. Click the little triangle next to the iPod, so that you can see the iPod's playlists under the iPod. Right-click on the first one, and select Open in New Window. A separate window showing the playlist should open. Arrange and resize that window and the main iTunes window, so that you can see both.

In the main iTunes window, create a new playlist in your iTunes library. Name it like the playlist shown in the other window. From your main iTunes music library, drag songs to that new playlist to reproduce the playlist that's on the iPod. Hopefully, all of your songs on the iPod are in your iTunes library.

Repeat for every playlist on the iPod, so that your iTunes library has the same set of playlists that are currently on your iPod. You may want to begin these "On iPod" playlist names with an underscore or other symbol, so that they all appear grouped together in the iTunes sidebar where the playlist are shown.

Now, do a Restore of your iPod. When the Restore completes, select the iPod in the sidebar. Over to the right, go the Music tab. Set it up to automatically sync music, and select only those playlists you just created down below. When you Apply the change, your iPod should have those playlists and all the songs on those playlists.

Going forward, any change you make to those playlists will sync automatically to the iPod, whenever it is connected or you click the Sync button. You don't need to have the iPod connected to update those playlists. If you ever need to do a Restore again, it will be easy to sync the music back after the Restore. If you lose or break the iPod, you can get a new one and easily sync the same playlists to it.