Songs can't be deleted or added.

when you add music to your itunes library, it copies them to the itunes music folder for itunes to manage it or itunes has every song twice in its library, to check whether itunes has not copied your music twice, view your music in LIST VIEW in itunes and if you see some songs has been copied twice delete on of them.
You can also delete the songs on your music folder to save disk space or you can leave them if you use another music player other than itunes.
But I think you should delete the files in your music folder.

You can have a try Leawo Tunes Cleaner. Just follow below steps. If you still have issues or have a massive music library in iTunes or other music folders that requires a more powerful and less time-consuming option, the third-party software like Leawo Tunes Cleaner can help you. It can not only automatically clean up duplicate songs in iTunes, but also automatically delete duplicate songs in other music folders. If you want to automatically remove duplicates in iTunes, the automatic duplicate remover might have the answer for you.
1. After kicking off Leawo Tunes Cleaner, click the "Clean-up Duplicate" entry. The program provides 2 duplicate scanning modes: Quick Scan mode and Deep Scan mode. Select one of them to scan duplicate songs.
2. You could delete duplicates in iTunes music library by directly clicking "Scan iTunes" button or click "Add" button to load music files for duplicates removing.
3. After loading source music files, click the "Scan" button on the upper-right corner to start scanning duplicates. The program would display all duplicates clearly and suggest what to remove. You could decide which duplicates to delete by checking them and then click the "Remove" button to remove duplicate songs.


For more details, check: How to Delete Duplicate Songs

If you go into the "add new tracks" settings and make sure that MP11 is not looking at folders you don't want it too, I.E. backup folders on an external HDD. You have to remove the files manually or, as I did, rename or move the folder(s) with the duplicates in and when MP11 tries to play them and can't find them you can set it to delete from library automaticaly.

works best when u add and delete from a music program like windows media, and go to sync tab

u can add them and delete from there

the only way to get the songs of to save then is to use a program to rip the songs from you ipod to your computer such as CopyTransSuite
as for adding and deleting songs, whe the ipod mounts on itunes uncheck the automatically sync music button and you can ckick the music folder and delete by right clicking and delete
if the songs are in someone elses library, if you sync your ipod to your computer the songs will be deleted.
use caution...
hope this helps

Go to my computer scroll to sansa or your MP3 player and open the music folder and open each sub folder and delete Songs manually then delete the folders them selfs then format

Try and drag and drop from your music folder to the media folder on the player make sure usb mode is msc this will show you all the folders Use your windows explorer for the transfer... much easier...If you don't have copies of your music copy to a folder on the computer first
Make sure you have it in MSC usb mode
Download and install run connect sansa when asked. Link
(http://mp3support.sandisk.com/sansa/Installer/1082/SansaUpdaterInstall.exe)
This has the manual also

take the songs you want off the mp3 copy and paste drag to desktop or your music folder and se if that works if not reboot comp rinse and repeat

Why does iTunes Duplicate Songs When Importing The issue that iTunes duplicates songs when importing is quite common and many users are not clear on the reasons for it. In order to clear up this confusion for iTunes users, here are some main causes of this trouble.
1. When you find your iTunes duplicates songs when importing to the library, it may result from improper settings of your program. You may have checked the options of "Keep iTunes media folder organized" and "Copy files to iTunes Media folder when adding to library". Thus, iTunes will repeatedly import a folder that is outside that iTunes Media folder into the library.
2. If the folder you add to iTunes library already has several duplicated songs, iTunes will import in all of them. Thus, you will find them duplicated in iTunes library.
3. If the songs you add to iTunes are untagged, iTunes will organize them all into "Unknown Artist/Unknown Album" and set the music name to "Filename". You will be unable to identify the song you need, for their name are almost the same.
4. iTunes does not have the feature to monitor your media folders when you import songs to the library. It just has trouble in detecting what is already on the library. This is one disadvantage of using iTunes itself to import songs.

Remove Duplicates after Importing with iTunes

Apart from avoiding duplicates before and in the process of importing, you can also use iTunes to remove duplicates after the importing. This aim can be achieved simply with the following steps.
1. Run iTunes on your computer and then click on "File" menu in the toolbar. Then you need to hit on "Library> Show Duplicate Items" in order.

2. You will see a list of all duplicates displayed in the right part of the iTunes screen. You can then click on a track or hold down the "Ctrl" key while hitting on multiple tracks to choose them.
3. When you have selected the items, you can click on "Song> Delete from Library" to remove the songs you have selected. The duplicated songs will disappear immediately from the iTunes interface. Thus, your iTunes library will be much clearer.

You should know that iTunes sometimes can confuse different mixes and slight variations shown in different albums. Therefore, you'd better make sure what you are removing is actually a duplicated and not a remix or version from a different album.


For more details, check: Why does iTunes Duplicate Songs When Importing

I don't know if you've inadvertently deleted the music folder, but that's what I did, when I deleted all the folders by mistake, thank heavens for in-store warrenty, they replaced it with another one. What I noticed on my replacement is synchronizing with media player doesn't work, it creates ghost folders and thinks music is there when it isn't, I don't understand it. Solution: open two windows for my music and sansa e280 music, then just drag and drop the folders; what I noticed is that in my music the folders are named by artist, and I prefer to see them by album, but when I view them in the player, I see the albums with the tracks in the right order.

You have to first change the USB mode on the player to MTP (as opposed to MSC). Forget using the Windows Media Player (yeah, I know). Go to Explorer, go to drive E or whatever your Sansa is listed as....open it and it will show different types of folders. Go to MUSIC folder. The songs are listed and you can delete, e.g. delete mp3 and keep WMA of the same song, or whatever else you want to delete.